1 =head1 BackupPC Introduction
3 This documentation describes BackupPC version __VERSION__,
4 released on __RELEASEDATE__.
8 BackupPC is a high-performance, enterprise-grade system for backing up
9 Unix, Linux, WinXX, and MacOSX PCs, desktops and laptops to a server's
10 disk. BackupPC is highly configurable and easy to install and maintain.
12 Given the ever decreasing cost of disks and raid systems, it is now
13 practical and cost effective to backup a large number of machines onto
14 a server's local disk or network storage. For some sites this might be
15 the complete backup solution. For other sites additional permanent
16 archives could be created by periodically backing up the server to tape.
24 A clever pooling scheme minimizes disk storage and disk I/O.
25 Identical files across multiple backups of the same or different PC
26 are stored only once (using hard links), resulting in substantial
27 savings in disk storage and disk writes.
31 Optional compression provides additional reductions in storage
32 (around 40%). The CPU impact of compression is low since only
33 new files (those not already in the pool) need to be compressed.
37 A powerful http/cgi user interface allows administrators to view
38 the current status, edit configuration, add/delete hosts, view log
39 files, and allows users to initiate and cancel backups and browse
40 and restore files from backups.
44 The http/cgi user interface has internationalization (i18n) support,
45 currently providing English, French, German, Spanish, Italian,
46 Dutch and Portuguese-Brazilian.
50 No client-side software is needed. On WinXX the standard smb protocol is
51 used to extract backup data. On linux, unix or MacOSX clients, rsync or
52 tar (over ssh/rsh/nfs) is used to extract backup data. Alternatively,
53 rsync can also be used on WinXX (using cygwin), and Samba could be
54 installed on the linux or unix client to provide smb shares).
58 Flexible restore options. Single files can be downloaded from
59 any backup directly from the CGI interface. Zip or Tar archives
60 for selected files or directories from any backup can also be
61 downloaded from the CGI interface. Finally, direct restore to
62 the client machine (using smb or tar) for selected files or
63 directories is also supported from the CGI interface.
67 BackupPC supports mobile environments where laptops are only
68 intermittently connected to the network and have dynamic IP addresses
69 (DHCP). Configuration settings allow machines connected via slower WAN
70 connections (eg: dial up, DSL, cable) to not be backed up, even if they
71 use the same fixed or dynamic IP address as when they are connected
76 Flexible configuration parameters allow multiple backups to be performed
77 in parallel, specification of which shares to backup, which directories
78 to backup or not backup, various schedules for full and incremental
79 backups, schedules for email reminders to users and so on. Configuration
80 parameters can be set system-wide or also on a per-PC basis.
84 Users are sent periodic email reminders if their PC has not
85 recently been backed up. Email content, timing and policies
90 BackupPC is Open Source software hosted by SourceForge.
100 A full backup is a complete backup of a share. BackupPC can be
101 configured to do a full backup at a regular interval (typically
102 weekly). BackupPC can be configured to keep a certain number
103 of full backups. Exponential expiry is also supported, allowing
104 full backups with various vintages to be kept (for example, a
105 settable number of most recent weekly fulls, plus a settable
106 number of older fulls that are 2, 4, 8, or 16 weeks apart).
108 =item Incremental Backup
110 An incremental backup is a backup of files that have changed
111 since the last successful full or incremental backup. Starting
112 in BackupPC 3.0 multi-level incrementals are supported.
113 A full backup has level 0. A new incremental of level N will
114 backup all files that have changed since the most recent backup
115 of a lower level. $Conf{IncrLevels} is used to specify the
116 level of each successive incremental. The default value is
117 all level 1, which makes the behavior the same as earlier
118 versions of BackupPC: each incremental will back up all the
119 files that changed since the last full (level 0).
121 For SMB and tar, BackupPC uses the modification time (mtime) to
122 determine which files have changed since the last lower-level
123 backup. That mean SMB and tar incrementals are not able to detect
124 deleted files, renamed files or new files whose modification time
125 is prior to the last lower-level backup.
127 Rsync is more clever: any files whose attributes have changed (ie: uid,
128 gid, mtime, modes, size) since the last full are backed up. Deleted,
129 new files and renamed files are detected by Rsync incrementals.
131 BackupPC can also be configured to keep a certain number of incremental
132 backups, and to keep a smaller number of very old incremental backups.
133 If multi-level incrementals are specified then it is likely that
134 more incrementals will need to be kept since lower-level incrementals
135 (and the full backup) are needed to reconstruct a higher-level
138 BackupPC "fills-in" incremental backups when browsing or restoring,
139 based on the levels of each backup, giving every backup a "full"
140 appearance. This makes browsing and restoring backups much easier:
141 you can restore from any one backup independent of whether it was
142 an incremental or full.
146 When a full backup fails or is canceled, and some files have already
147 been backed up, BackupPC keeps a partial backup containing just the
148 files that were backed up successfully. The partial backup is removed
149 when the next successful backup completes, or if another full backup
150 fails resulting in a newer partial backup. A failed full backup
151 that has not backed up any files, or any failed incremental backup,
152 is removed; no partial backup is saved in these cases.
154 The partial backup may be browsed or used to restore files just like
155 a successful full or incremental backup.
157 With the rsync transfer method the partial backup is used to resume
158 the next full backup, avoiding the need to retransfer the file data
159 already in the partial backup.
161 =item Identical Files
163 BackupPC pools identical files using hardlinks. By "identical
164 files" we mean files with identical contents, not necessary the
165 same permissions, ownership or modification time. Two files might
166 have different permissions, ownership, or modification time but
167 will still be pooled whenever the contents are identical. This
168 is possible since BackupPC stores the file meta-data (permissions,
169 ownership, and modification time) separately from the file contents.
173 Based on your site's requirements you need to decide what your backup
174 policy is. BackupPC is not designed to provide exact re-imaging of
175 failed disks. See L<Limitations|limitations> for more information.
176 However, the addition of tar transport for linux/unix clients, plus
177 full support for special file types and unix attributes in v1.4.0
178 likely means an exact image of a linux/unix file system can be made.
180 BackupPC saves backups onto disk. Because of pooling you can relatively
181 economically keep several weeks of old backups.
183 At some sites the disk-based backup will be adequate, without a
184 secondary tape backup. This system is robust to any single failure: if a
185 client disk fails or loses files, the BackupPC server can be used to
186 restore files. If the server disk fails, BackupPC can be restarted on a
187 fresh file system, and create new backups from the clients. The chance
188 of the server disk failing can be made very small by spending more money
189 on increasingly better RAID systems. However, there is still the risk
190 of catastrophic events like fires or earthquakes that can destroy
191 both the BackupPC server and the clients it is backing up if they
192 are physically nearby.
194 Some sites might choose to do periodic backups to tape or cd/dvd.
195 This backup can be done perhaps weekly using the archive function of
198 Other users have reported success with removable disks to rotate the
199 BackupPC data drives, or using rsync to mirror the BackupPC data pool
208 =item BackupPC home page
210 The BackupPC Open Source project is hosted on SourceForge. The
211 home page can be found at:
213 http://backuppc.sourceforge.net
215 This page has links to the current documentation, the SourceForge
216 project page and general information.
218 =item SourceForge project
220 The SourceForge project page is at:
222 http://sourceforge.net/projects/backuppc
224 This page has links to the current releases of BackupPC.
228 BackupPC has a FAQ at L<http://backuppc.sourceforge.net/faq>.
232 Three BackupPC mailing lists exist for announcements (backuppc-announce),
233 developers (backuppc-devel), and a general user list for support, asking
234 questions or any other topic relevant to BackupPC (backuppc-users).
236 The lists are archived on SourceForge and Gmane. The SourceForge lists
237 are not always up to date and the searching is limited, so Gmane is
238 a good alternative. See:
240 http://news.gmane.org/index.php?prefix=gmane.comp.sysutils.backup.backuppc
241 http://sourceforge.net/mailarchive/forum.php?forum_id=503
243 You can subscribe to these lists by visiting:
245 http://lists.sourceforge.net/lists/listinfo/backuppc-announce
246 http://lists.sourceforge.net/lists/listinfo/backuppc-users
247 http://lists.sourceforge.net/lists/listinfo/backuppc-devel
249 The backuppc-announce list is moderated and is used only for
250 important announcements (eg: new versions). It is low traffic.
251 You only need to subscribe to one of backuppc-announce and
252 backuppc-users: backuppc-users also receives any messages on
255 The backuppc-devel list is only for developers who are working on BackupPC.
256 Do not post questions or support requests there. But detailed technical
257 discussions should happen on this list.
259 To post a message to the backuppc-users list, send an email to
261 backuppc-users@lists.sourceforge.net
263 Do not send subscription requests to this address!
265 =item Other Programs of Interest
267 If you want to mirror linux or unix files or directories to a remote server
268 you should use rsync, L<http://rsync.samba.org>. BackupPC uses
269 rsync as a transport mechanism; if you are already an rsync user you
270 can think of BackupPC as adding efficient storage (compression and
271 pooling) and a convenient user interface to rsync.
273 Two popular open source packages that do tape backup are
274 Amanda (L<http://www.amanda.org>)
275 and Bacula (L<http://www.bacula.org>).
276 Amanda can also backup WinXX machines to tape using samba.
277 These packages can be used as back ends to BackupPC to backup the
278 BackupPC server data to tape.
280 Various programs and scripts use rsync to provide hardlinked backups.
281 See, for example, Mike Rubel's site (L<http://www.mikerubel.org/computers/rsync_snapshots>),
282 JW Schultz's dirvish (L<http://www.dirvish.org/>),
283 Ben Escoto's rdiff-backup (L<http://www.nongnu.org/rdiff-backup>),
284 and John Bowman's rlbackup (L<http://www.math.ualberta.ca/imaging/rlbackup>).
286 Unison is a utility that can do two-way, interactive, synchronization.
287 See L<http://freshmeat.net/projects/unison>. An external wrapper around
288 rsync that maintains transfer data to enable two-way synchronization is
289 drsync; see L<http://freshmeat.net/projects/drsync>.
291 BackupPC provides many additional features, such as compressed storage,
292 hardlinking any matching files (rather than just files with the same name),
293 and storing special files without root privileges. But these other programs
294 provide simple, effective and fast solutions and are definitely worthy of
301 The new features planned for future releases of BackupPC
302 are at L<http://backuppc.sourceforge.net/faq/roadMap.html>.
304 Comments and suggestions are welcome.
308 BackupPC is free. I work on BackupPC because I enjoy doing it and I like
309 to contribute to the open source community.
311 BackupPC already has more than enough features for my own needs. The
312 main compensation for continuing to work on BackupPC is knowing that
313 more and more people find it useful. So feedback is certainly
314 appreciated, both positive and negative.
316 Beyond being a satisfied user and telling other people about it, everyone
317 is encouraged to add links to L<http://backuppc.sourceforge.net>
318 (I'll see them via Google) or otherwise publicize BackupPC. Unlike
319 the commercial products in this space, I have a zero budget (in both
320 time and money) for marketing, PR and advertising, so it's up to
321 all of you! Feel free to vote for BackupPC at
322 L<http://freshmeat.net/projects/backuppc>.
324 Also, everyone is encouraged to contribute patches, bug reports, feature
325 and design suggestions, new code, FAQs, and documentation corrections or
326 improvements. Answering questions on the mail list is a big help too.
328 =head1 Installing BackupPC
338 A linux, solaris, or unix based server with a substantial amount of free
339 disk space (see the next section for what that means). The CPU and disk
340 performance on this server will determine how many simultaneous backups
341 you can run. You should be able to run 4-8 simultaneous backups on a
342 moderately configured server.
344 Several users have reported significantly better performance using
345 reiser compared to ext3 for the BackupPC data file system. It is
346 also recommended you consider either an LVM or raid setup (either
347 in HW or SW; eg: 3Ware RAID5) so that you can expand the
348 file system as necessary.
350 When BackupPC starts with an empty pool, all the backup data will be
351 written to the pool on disk. After more backups are done, a higher
352 percentage of incoming files will already be in the pool. BackupPC is
353 able to avoid writing to disk new files that are already in the pool.
354 So over time disk writes will reduce significantly (by perhaps a factor
355 of 20 or more), since eventually 95% or more of incoming backup files
356 are typically in the pool. Disk reads from the pool are still needed to
357 do file compares to verify files are an exact match. So, with a mature
358 pool, if a relatively fast client generates data at say 1MB/sec, and you
359 run 4 simultaneous backups, there will be an average server disk load of
360 about 4MB/sec reads and 0.2MB/sec writes (assuming 95% of the incoming
361 files are in the pool). These rates will be perhaps 40% lower if
366 Perl version 5.6.0 or later. BackupPC has been tested with
367 version 5.6.x, and 5.8.x. If you don't have perl, please
368 see L<http://www.cpan.org>.
372 Perl modules Compress::Zlib, Archive::Zip and File::RsyncP. Try "perldoc
373 Compress::Zlib" and "perldoc Archive::Zip" to see if you have these
374 modules. If not, fetch them from L<http://www.cpan.org> and see the
375 instructions below for how to build and install them.
377 The File::RsyncP module is available from L<http://perlrsync.sourceforge.net>
378 or CPAN. You'll need to install the File::RsyncP module if you want to use
379 Rsync as a transport method.
383 If you are using smb to backup WinXX machines you need smbclient and
384 nmblookup from the samba package. You will also need nmblookup if
385 you are backing up linux/unix DHCP machines. See L<http://www.samba.org>.
386 Samba versions 3.x are stable and now recommended instead of 2.x.
388 See L<http://www.samba.org> for source and binaries. It's pretty easy to
389 fetch and compile samba, and just grab smbclient and nmblookup, without
390 doing the installation. Alternatively, L<http://www.samba.org> has binary
391 distributions for most platforms.
395 If you are using tar to backup linux/unix machines you should have version
396 1.13.7 at a minimum, with version 1.13.20 or higher recommended. Use
397 "tar --version" to check your version. Various GNU mirrors have the newest
398 versions of tar, see for example L<http://www.funet.fi/pub/gnu/alpha/gnu/tar>.
399 As of July 2006 the latest version is 1.15.1.
403 If you are using rsync to backup linux/unix machines you should have
404 version 2.6.3 or higher on each client machine. See
405 L<http://rsync.samba.org>. Use "rsync --version" to check your version.
407 For BackupPC to use Rsync you will also need to install the perl
408 File::RsyncP module, which is available from
409 L<http://perlrsync.sourceforge.net>.
410 Version 0.70 or later is required.
414 The Apache web server, see L<http://www.apache.org>, preferably built
415 with mod_perl support.
419 =head2 How much disk space do I need?
421 Here's one real example for an environment that is backing up 65 laptops
422 with compression off. Each full backup averages 3.2GB. Each incremental
423 backup averages about 0.2GB. Storing one full backup and two incremental
424 backups per laptop is around 240GB of raw data. But because of the
425 pooling of identical files, only 87GB is used. This is without
428 Another example, with compression on: backing up 95 laptops, where
429 each backup averages 3.6GB and each incremental averages about 0.3GB.
430 Keeping three weekly full backups, and six incrementals is around
431 1200GB of raw data. Because of pooling and compression, only 150GB
434 Here's a rule of thumb. Add up the disk usage of all the machines you
435 want to backup (210GB in the first example above). This is a rough
436 minimum space estimate that should allow a couple of full backups and at
437 least half a dozen incremental backups per machine. If compression is on
438 you can reduce the storage requirements by maybe 30-40%. Add some margin
439 in case you add more machines or decide to keep more old backups.
441 Your actual mileage will depend upon the types of clients, operating
442 systems and applications you have. The more uniform the clients and
443 applications the bigger the benefit from pooling common files.
445 For example, the Eudora email tool stores each mail folder in a separate
446 file, and attachments are extracted as separate files. So in the sadly
447 common case of a large attachment emailed to many recipients, Eudora
448 will extract the attachment into a new file. When these machines are
449 backed up, only one copy of the file will be stored on the server, even
450 though the file appears in many different full or incremental backups. In
451 this sense Eudora is a "friendly" application from the point of view of
452 backup storage requirements.
454 An example at the other end of the spectrum is Outlook. Everything
455 (email bodies, attachments, calendar, contact lists) is stored in a
456 single file, which often becomes huge. Any change to this file requires
457 a separate copy of the file to be saved during backup. Outlook is even
458 more troublesome, since it keeps this file locked all the time, so it
459 cannot be read by smbclient whenever Outlook is running. See the
460 L<Limitations|limitations> section for more discussion of this problem.
462 In addition to total disk space, you shold make sure you have
463 plenty of inodes on your BackupPC data partition. Some users have
464 reported running out of inodes on their BackupPC data partition.
465 So even if you have plenty of disk space, BackupPC will report
466 failures when the inodes are exhausted. This is a particular
467 problem with ext2/ext3 file systems that have a fixed number of
468 inodes when the file system is built. Use "df -i" to see your
471 =head2 Step 1: Getting BackupPC
473 Some linux distributions now include BackupPC. The Debian
474 distribution, supprted by Ludovic Drolez, can be found at
475 L<http://packages.debian.org/backuppc>; it should be included
476 in the next stable Debian release. On Debian, BackupPC can
477 be installed with the command:
479 apt-get install backuppc
481 In the future there might be packages for Gentoo and other
482 linux flavors. If the packaged version is older than the
483 released version then you will probably want to install the
484 latest version as described below.
486 Otherwise, manually fetching and installing BackupPC is easy.
487 Start by downloading the latest version from
488 L<http://backuppc.sourceforge.net>. Hit the "Code" button,
489 then select the "backuppc" or "backuppc-beta" package and
490 download the latest version.
492 =head2 Step 2: Installing the distribution
494 First off, there are three perl modules you should install.
495 These are all optional, but highly recommended:
501 To enable compression, you will need to install Compress::Zlib
502 from L<http://www.cpan.org>.
503 You can run "perldoc Compress::Zlib" to see if this module is installed.
507 To support restore via Zip archives you will need to install
508 Archive::Zip, also from L<http://www.cpan.org>.
509 You can run "perldoc Archive::Zip" to see if this module is installed.
513 To support the RSS feature you will need to install XML::RSS, also from
514 L<http://www.cpan.org>. There is not need to install this module if you
515 don't plan on using RSS. You can run "perldoc XML::RSS" to see if this
520 To use rsync and rsyncd with BackupPC you will need to install File::RsyncP.
521 You can run "perldoc File::RsyncP" to see if this module is installed.
522 File::RsyncP is available from L<http://perlrsync.sourceforge.net>.
523 Version 0.52 or later is required.
527 To build and install these packages, fetch the tar.gz file and
528 then run these commands:
530 tar zxvf Archive-Zip-1.16.tar.gz
537 The same sequence of commands can be used for each module.
539 Now let's move onto BackupPC itself. After fetching
540 BackupPC-__VERSION__.tar.gz, run these commands as root:
542 tar zxf BackupPC-__VERSION__.tar.gz
543 cd BackupPC-__VERSION__
546 In the future this release might also have patches available on the
547 SourceForge site. These patch files are text files, with a name of
550 BackupPC-__VERSION__plN.diff
552 where N is the patch level, eg: pl2 is patch-level 2. These
553 patch files are cumulative: you only need apply the last patch
554 file, not all the earlier patch files. If a patch file is
555 available, eg: BackupPC-__VERSION__pl2.diff, you should apply
556 the patch after extracting the tar file:
558 # fetch BackupPC-__VERSION__.tar.gz
559 # fetch BackupPC-__VERSION__pl2.diff
560 tar zxf BackupPC-__VERSION__.tar.gz
561 cd BackupPC-__VERSION__
562 patch -p0 < ../BackupPC-__VERSION__pl2.diff
565 A patch file includes comments that describe that bug fixes
566 and changes. Feel free to review it before you apply the patch.
568 The configure.pl script also accepts command-line options if you
569 wish to run it in a non-interactive manner. It has self-contained
570 documentation for all the command-line options, which you can
575 Starting with BackupPC 3.0.0, the configure.pl script by default
576 complies with the file system hierarchy conventions. The major
577 difference compared to earlier versions is that by default
578 configuration files will be stored in /etc/BackupPC
579 rather than below the data directory, __TOPDIR__/conf,
580 and the log files will be stored in /var/log/BackupPC.
581 rather than below the data directory, __TOPDIR__/log.
583 If you are upgrading from an earlier version the configure.pl script
584 will keep the configuration files and log files in their original
587 When you run configure.pl you will be prompted for the full paths
588 of various executables, and you will be prompted for the following
595 It is best if BackupPC runs as a special user, eg backuppc, that has
596 limited privileges. It is preferred that backuppc belongs to a system
597 administrator group so that sys admin members can browse backuppc files,
598 edit the configuration files and so on. Although configurable, the
599 default settings leave group read permission on pool files, so make
600 sure the BackupPC user's group is chosen restrictively.
602 On this installation, this is __BACKUPPCUSER__.
604 For security purposes you might choose to configure the BackupPC
605 user with the shell set to /bin/false. Since you might need to
606 run some BackupPC programs as the BackupPC user for testing
607 purposes, you can use the -s option to su to explicitly run
610 su -s /bin/bash __BACKUPPCUSER__
612 Depending upon your configuration you might also need the -l option.
616 You need to decide where to put the data directory, below which
617 all the BackupPC data is stored. This needs to be a big file system.
619 On this installation, this is __TOPDIR__.
621 =item Install Directory
623 You should decide where the BackupPC scripts, libraries and documentation
624 should be installed, eg: /usr/local/BackupPC.
626 On this installation, this is __INSTALLDIR__.
628 =item CGI bin Directory
630 You should decide where the BackupPC CGI script resides. This will
631 usually be below Apache's cgi-bin directory.
633 On this installation, this is __CGIDIR__.
635 =item Apache image directory
637 A directory where BackupPC's images are stored so that Apache can
638 serve them. This should be somewhere under Apache's DocumentRoot
641 =item Config and Log directories
643 In this installation the configuration and log directories are
644 located in the following locations:
646 __CONFDIR__/config.pl main config file
647 __CONFDIR__/hosts hosts file
648 __CONFDIR__/pc/HOST.pl per-pc config file
649 __LOGDIR__/BackupPC log files, pid, status
651 The configure.pl script doesn't prompt for these locations but
652 they can be set for new installations using command-line options.
656 =head2 Step 3: Setting up config.pl
658 After running configure.pl, browse through the config file,
659 __CONFDIR__/config.pl, and make sure all the default settings
660 are correct. In particular, you will need to decide whether to use
661 smb, tar or rsync transport (or whether to set it on a per-PC basis)
662 and set the relevant parameters for that transport method.
663 See the section L<Client Setup|step 5: client setup> for more details.
665 =head2 Step 4: Setting up the hosts file
667 The file __CONFDIR__/hosts contains the list of clients to backup.
668 BackupPC reads this file in three cases:
678 When BackupPC is sent a HUP (-1) signal. Assuming you installed the
679 init.d script, you can also do this with "/etc/init.d/backuppc reload".
683 When the modification time of the hosts file changes. BackupPC
684 checks the modification time once during each regular wakeup.
688 Whenever you change the hosts file (to add or remove a host) you can
689 either do a kill -HUP BackupPC_pid or simply wait until the next regular
692 Each line in the hosts file contains three fields, separated
699 This is typically the host name or NetBios name of the client machine
700 and should be in lower case. The host name can contain spaces (escape
701 with a backslash), but it is not recommended.
703 Please read the section L<How BackupPC Finds Hosts|how backuppc finds hosts>.
705 In certain cases you might want several distinct clients to refer
706 to the same physical machine. For example, you might have a database
707 you want to backup, and you want to bracket the backup of the database
708 with shutdown/restart using $Conf{DumpPreUserCmd} and $Conf{DumpPostUserCmd}.
709 But you also want to backup the rest of the machine while the database
710 is still running. In the case you can specify two different clients in
711 the host file, using any mnemonic name (eg: myhost_mysql and myhost), and
712 use $Conf{ClientNameAlias} in myhost_mysql's config.pl to specify the
713 real host name of the machine.
717 Starting with v2.0.0 the way hosts are discovered has changed and now
718 in most cases you should specify 0 for the DHCP flag, even if the host
719 has a dynamically assigned IP address.
720 Please read the section L<How BackupPC Finds Hosts|how backuppc finds hosts>
721 to understand whether you need to set the DHCP flag.
723 You only need to set DHCP to 1 if your client machine doesn't
724 respond to the NetBios multicast request:
728 but does respond to a request directed to its IP address:
732 If you do set DHCP to 1 on any client you will need to specify the range of
733 DHCP addresses to search is specified in $Conf{DHCPAddressRanges}.
735 Note also that the $Conf{ClientNameAlias} feature does not work for
736 clients with DHCP set to 1.
740 This should be the unix login/email name of the user who "owns" or uses
741 this machine. This is the user who will be sent email about this
742 machine, and this user will have permission to stop/start/browse/restore
743 backups for this host. Leave this blank if no specific person should
744 receive email or be allowed to stop/start/browse/restore backups
745 for this host. Administrators will still have full permissions.
749 Additional user names, separate by commas and with no white space,
750 can be specified. These users will also have full permission in
751 the CGI interface to stop/start/browse/restore backups for this host.
752 These users will not be sent email about this host.
756 The first non-comment line of the hosts file is special: it contains
757 the names of the columns and should not be edited.
759 Here's a simple example of a hosts file:
761 host dhcp user moreUsers
762 farside 0 craig jim,dave
765 =head2 Step 5: Client Setup
767 Three methods for getting backup data from a client are supported: smb,
768 tar and rsync. Smb or rsync are the preferred methods for WinXX clients
769 and rsync or tar are the preferred methods for linux/unix/MacOSX clients.
771 The transfer method is set using the $Conf{XferMethod} configuration
772 setting. If you have a mixed environment (ie: you will use smb for some
773 clients and tar for others), you will need to pick the most common
774 choice for $Conf{XferMethod} for the main config.pl file, and then
775 override it in the per-PC config file for those hosts that will use
776 the other method. (Or you could run two completely separate instances
777 of BackupPC, with different data directories, one for WinXX and the
778 other for linux/unix, but then common files between the different
779 machine types will duplicated.)
781 Here are some brief client setup notes:
787 One setup for WinXX clients is to set $Conf{XferMethod} to "smb".
788 Actually, rsyncd is the better method for WinXX if you are prepared to
789 run rsync/cygwin on your WinXX client.
791 If you want to use rsyncd for WinXX clients you can find a pre-packaged
792 zip file on L<http://backuppc.sourceforge.net>. The package is called
793 cygwin-rsync. It contains rsync.exe, template setup files and the
794 minimal set of cygwin libraries for everything to run. The README file
795 contains instructions for running rsync as a service, so it starts
796 automatically everytime you boot your machine. If you use rsync
797 to backup WinXX machines, be sure to set $Conf{ClientCharset}
798 correctly (eg: 'cp1252') so that the WinXX file name encoding is
799 correctly converted to utf8.
801 Otherwise, to use SMB, you can either create shares for the data you want
802 to backup or your can use the existing C$ share. To create a new
803 share, open "My Computer", right click on the drive (eg: C), and
804 select "Sharing..." (or select "Properties" and select the "Sharing"
805 tab). In this dialog box you can enable sharing, select the share name
808 All Windows NT based OS (NT, 2000, XP Pro), are configured by default
809 to share the entire C drive as C$. This is a special share used for
810 various administration functions, one of which is to grant access to backup
811 operators. All you need to do is create a new domain user, specifically
812 for backup. Then add the new backup user to the built in "Backup
813 Operators" group. You now have backup capability for any directory on
814 any computer in the domain in one easy step. This avoids using
815 administrator accounts and only grants permission to do exactly what you
816 want for the given user, i.e.: backup.
817 Also, for additional security, you may wish to deny the ability for this
818 user to logon to computers in the default domain policy.
820 If this machine uses DHCP you will also need to make sure the
821 NetBios name is set. Go to Control Panel|System|Network Identification
822 (on Win2K) or Control Panel|System|Computer Name (on WinXP).
823 Also, you should go to Control Panel|Network Connections|Local Area
824 Connection|Properties|Internet Protocol (TCP/IP)|Properties|Advanced|WINS
825 and verify that NetBios is not disabled.
827 The relevant configuration settings are $Conf{SmbShareName},
828 $Conf{SmbShareUserName}, $Conf{SmbSharePasswd}, $Conf{SmbClientPath},
829 $Conf{SmbClientFullCmd}, $Conf{SmbClientIncrCmd} and
830 $Conf{SmbClientRestoreCmd}.
832 BackupPC needs to know the smb share user name and password for a
833 client machine that uses smb. The user name is specified in
834 $Conf{SmbShareUserName}. There are four ways to tell BackupPC the
841 As an environment variable BPC_SMB_PASSWD set before BackupPC starts.
842 If you start BackupPC manually the BPC_SMB_PASSWD variable must be set
843 manually first. For backward compatibility for v1.5.0 and prior, the
844 environment variable PASSWD can be used if BPC_SMB_PASSWD is not set.
845 Warning: on some systems it is possible to see environment variables of
850 Alternatively the BPC_SMB_PASSWD setting can be included in
851 /etc/init.d/backuppc, in which case you must make sure this file
852 is not world (other) readable.
856 As a configuration variable $Conf{SmbSharePasswd} in
857 __CONFDIR__/config.pl. If you put the password
858 here you must make sure this file is not world (other) readable.
862 As a configuration variable $Conf{SmbSharePasswd} in the per-PC
863 configuration file (__CONFDIR__/pc/$host.pl or
864 __TOPDIR__/pc/$host/config.pl in non-FHS versions of BackupPC).
865 You will have to use this option if the smb share password is different
866 for each host. If you put the password here you must make sure this file
867 is not world (other) readable.
871 Placement and protection of the smb share password is a possible
872 security risk, so please double-check the file and directory
873 permissions. In a future version there might be support for
874 encryption of this password, but a private key will still have to
875 be stored in a protected place. Suggestions are welcome.
877 As an alternative to setting $Conf{XferMethod} to "smb" (using
878 smbclient) for WinXX clients, you can use an smb network filesystem (eg:
879 ksmbfs or similar) on your linux/unix server to mount the share,
880 and then set $Conf{XferMethod} to "tar" (use tar on the network
881 mounted file system).
883 Also, to make sure that file names with special characters are correctly
884 transferred by smbclient you should make sure that the smb.conf file
890 UTF8 is the default setting, so if the parameter is missing then it
891 is ok. With this setting $Conf{ClientCharset} should be emtpy,
892 since smbclient has already converted the file names to utf8.
896 The preferred setup for linux/unix clients is to set $Conf{XferMethod}
897 to "rsync", "rsyncd" or "tar".
899 You can use either rsync, smb, or tar for linux/unix machines. Smb requires
900 that the Samba server (smbd) be run to provide the shares. Since the smb
901 protocol can't represent special files like symbolic links and fifos,
902 tar and rsync are the better transport methods for linux/unix machines.
903 (In fact, by default samba makes symbolic links look like the file or
904 directory that they point to, so you could get an infinite loop if a
905 symbolic link points to the current or parent directory. If you really
906 need to use Samba shares for linux/unix backups you should turn off the
907 "follow symlinks" samba config setting. See the smb.conf manual page.)
909 The requirements for each Xfer Method are:
915 You must have GNU tar on the client machine. Use "tar --version"
916 or "gtar --version" to verify. The version should be at least
917 1.13.7, and 1.13.20 or greater is recommended. Tar is run on
918 the client machine via rsh or ssh.
920 The relevant configuration settings are $Conf{TarClientPath},
921 $Conf{TarShareName}, $Conf{TarClientCmd}, $Conf{TarFullArgs},
922 $Conf{TarIncrArgs}, and $Conf{TarClientRestoreCmd}.
926 You should have at least rsync 2.6.3, and the latest version is
927 recommended. Rsync is run on the remote client via rsh or ssh.
929 The relevant configuration settings are $Conf{RsyncClientPath},
930 $Conf{RsyncClientCmd}, $Conf{RsyncClientRestoreCmd}, $Conf{RsyncShareName},
931 $Conf{RsyncArgs}, and $Conf{RsyncRestoreArgs}.
935 You should have at least rsync 2.6.3, and the latest version is
936 recommended. In this case the rsync daemon should be running on
937 the client machine and BackupPC connects directly to it.
939 The relevant configuration settings are $Conf{RsyncdClientPort},
940 $Conf{RsyncdUserName}, $Conf{RsyncdPasswd}, $Conf{RsyncdAuthRequired},
941 $Conf{RsyncShareName}, $Conf{RsyncArgs}, and $Conf{RsyncRestoreArgs}.
942 $Conf{RsyncShareName} is the name of an rsync module (ie: the thing
943 in square brackets in rsyncd's conf file -- see rsyncd.conf), not a
946 Be aware that rsyncd will remove the leading '/' from path names in
947 symbolic links if you specify "use chroot = no" in the rsynd.conf file.
948 See the rsyncd.conf manual page for more information.
952 You need to set $Conf{ClientCharset} to the client's charset so that
953 file names are correctly converted to utf8. Use "locale charmap"
954 on the client to see its charset.
956 For linux/unix machines you should not backup "/proc". This directory
957 contains a variety of files that look like regular files but they are
958 special files that don't need to be backed up (eg: /proc/kcore is a
959 regular file that contains physical memory). See $Conf{BackupFilesExclude}.
960 It is safe to back up /dev since it contains mostly character-special
961 and block-special files, which are correctly handed by BackupPC
962 (eg: backing up /dev/hda5 just saves the block-special file information,
963 not the contents of the disk).
965 Alternatively, rather than backup all the file systems as a single
966 share ("/"), it is easier to restore a single file system if you backup
967 each file system separately. To do this you should list each file system
968 mount point in $Conf{TarShareName} or $Conf{RsyncShareName}, and add the
969 --one-file-system option to $Conf{TarClientCmd} or add --one-file-system
970 (note the different punctuation) to $Conf{RsyncArgs}. In this case there
971 is no need to exclude /proc explicitly since it looks like a different
974 Next you should decide whether to run tar over ssh, rsh or nfs. Ssh is
975 the preferred method. Rsh is not secure and therefore not recommended.
976 Nfs will work, but you need to make sure that the BackupPC user (running
977 on the server) has sufficient permissions to read all the files below
980 Ssh allows BackupPC to run as a privileged user on the client (eg:
981 root), since it needs sufficient permissions to read all the backup
982 files. Ssh is setup so that BackupPC on the server (an otherwise low
983 privileged user) can ssh as root on the client, without being prompted
984 for a password. There are two common versions of ssh: v1 and v2. Here
985 are some instructions for one way to setup ssh. (Check which version
986 of SSH you have by typing "ssh" or "man ssh".)
990 In general this should be similar to Linux/Unix machines.
991 In versions 10.4 and later, the native MacOSX tar works,
992 and also supports resource forks. xtar is another option,
993 and rsync works too (although the MacOSX-supplied rsync
994 has an extension for extended attributes that is not
995 compatible with standard rsync).
999 SSH is a secure way to run tar or rsync on a backup client to extract
1000 the data. SSH provides strong authentication and encryption of
1003 Note that if you run rsyncd (rsync daemon), ssh is not used.
1004 In this case, rsyncd provides its own authentication, but there
1005 is no encryption of network data. If you want encryption of
1006 network data you can use ssh to create a tunnel, or use a
1007 program like stunnel. If someone submits instructions I
1009 Setup instructions for ssh are at
1010 L<http://backuppc.sourceforge.net/faq/ssh.html>.
1012 =item Clients that use DHCP
1014 If a client machine uses DHCP BackupPC needs some way to find the
1015 IP address given the host name. One alternative is to set dhcp
1016 to 1 in the hosts file, and BackupPC will search a pool of IP
1017 addresses looking for hosts. More efficiently, it is better to
1018 set dhcp = 0 and provide a mechanism for BackupPC to find the
1019 IP address given the host name.
1021 For WinXX machines BackupPC uses the NetBios name server to determine
1022 the IP address given the host name.
1023 For unix machines you can run nmbd (the NetBios name server) from
1024 the Samba distribution so that the machine responds to a NetBios
1025 name request. See the manual page and Samba documentation for more
1028 Alternatively, you can set $Conf{NmbLookupFindHostCmd} to any command
1029 that returns the IP address given the host name.
1031 Please read the section L<How BackupPC Finds Hosts|how backuppc finds hosts>
1036 =head2 Step 6: Running BackupPC
1038 The installation contains an init.d backuppc script that can be copied
1039 to /etc/init.d so that BackupPC can auto-start on boot.
1040 See init.d/README for further instructions.
1042 BackupPC should be ready to start. If you installed the init.d script,
1043 then you should be able to run BackupPC with:
1045 /etc/init.d/backuppc start
1047 (This script can also be invoked with "stop" to stop BackupPC and "reload"
1048 to tell BackupPC to reload config.pl and the hosts file.)
1052 __INSTALLDIR__/bin/BackupPC -d
1054 as user __BACKUPPCUSER__. The -d option tells BackupPC to run as a daemon
1055 (ie: it does an additional fork).
1057 Any immediate errors will be printed to stderr and BackupPC will quit.
1058 Otherwise, look in __LOGDIR__/LOG and verify that BackupPC reports
1059 it has started and all is ok.
1061 =head2 Step 7: Talking to BackupPC
1063 You should verify that BackupPC is running by using BackupPC_serverMesg.
1064 This sends a message to BackupPC via the unix (or TCP) socket and prints
1065 the response. Like all BackupPC programs, BackupPC_serverMesg
1066 should be run as the BackupPC user (__BACKUPPCUSER__), so you
1071 before running BackupPC_serverMesg. If the BackupPC user is
1072 configured with /bin/false as the shell, you can use the -s
1073 option to su to explicitly run a shell, eg:
1075 su -s /bin/bash __BACKUPPCUSER__
1077 Depending upon your configuration you might also need
1080 You can request status information and start and stop backups using this
1081 interface. This socket interface is mainly provided for the CGI interface
1082 (and some of the BackupPC sub-programs use it too). But right now we just
1083 want to make sure BackupPC is happy. Each of these commands should
1084 produce some status output:
1086 __INSTALLDIR__/bin/BackupPC_serverMesg status info
1087 __INSTALLDIR__/bin/BackupPC_serverMesg status jobs
1088 __INSTALLDIR__/bin/BackupPC_serverMesg status hosts
1090 The output should be some hashes printed with Data::Dumper. If it
1091 looks cryptic and confusing, and doesn't look like an error message,
1094 The jobs status should initially show just BackupPC_trashClean.
1095 The hosts status should produce a list of every host you have listed
1096 in __CONFDIR__/hosts as part of a big cryptic output line.
1098 You can also request that all hosts be queued:
1100 __INSTALLDIR__/bin/BackupPC_serverMesg backup all
1102 At this point you should make sure the CGI interface works since
1103 it will be much easier to see what is going on. That's our
1106 =head2 Step 8: Checking email delivery
1108 The script BackupPC_sendEmail sends status and error emails to
1109 the administrator and users. It is usually run each night
1110 by BackupPC_nightly.
1112 To verify that it can run sendmail and deliver email correctly
1113 you should ask it to send a test email to you:
1116 __INSTALLDIR__/bin/BackupPC_sendEmail -u MYNAME@MYDOMAIN.COM
1118 BackupPC_sendEmail also takes a -c option that checks if BackupPC
1119 is running, and it sends an email to $Conf{EMailAdminUserName}
1120 if it is not. That can be used as a keep-alive check by adding
1122 __INSTALLDIR__/bin/BackupPC_sendEmail -c
1124 to __BACKUPPCUSER__'s cron.
1126 The -t option to BackupPC_sendEmail causes it to print the email
1127 message instead of invoking sendmail to deliver the message.
1129 =head2 Step 9: CGI interface
1131 The CGI interface script, BackupPC_Admin, is a powerful and flexible
1132 way to see and control what BackupPC is doing. It is written for an
1133 Apache server. If you don't have Apache, see L<http://www.apache.org>.
1135 There are two options for setting up the CGI interface: standard
1136 mode and using mod_perl. Mod_perl provides much higher performance
1137 (around 15x) and is the best choice if your Apache was built with
1138 mod_perl support. To see if your apache was built with mod_perl
1141 httpd -l | egrep mod_perl
1143 If this prints mod_perl.c then your Apache supports mod_perl.
1145 Using mod_perl with BackupPC_Admin requires a dedicated Apache
1146 to be run as the BackupPC user (__BACKUPPCUSER__). This is
1147 because BackupPC_Admin needs permission to access various files
1148 in BackupPC's data directories. In contrast, the standard
1149 installation (without mod_perl) solves this problem by having
1150 BackupPC_Admin installed as setuid to the BackupPC user, so that
1151 BackupPC_Admin runs as the BackuPC user.
1153 Here are some specifics for each setup:
1157 =item Standard Setup
1159 The CGI interface should have been installed by the configure.pl script
1160 in __CGIDIR__/BackupPC_Admin. BackupPC_Admin should have been installed
1161 as setuid to the BackupPC user (__BACKUPPCUSER__), in addition to user
1162 and group execute permission.
1164 You should be very careful about permissions on BackupPC_Admin and
1165 the directory __CGIDIR__: it is important that normal users cannot
1166 directly execute or change BackupPC_Admin, otherwise they can access
1167 backup files for any PC. You might need to change the group ownership
1168 of BackupPC_Admin to a group that Apache belongs to so that Apache
1169 can execute it (don't add "other" execute permission!).
1170 The permissions should look like this:
1172 ls -l __CGIDIR__/BackupPC_Admin
1173 -swxr-x--- 1 __BACKUPPCUSER__ web 82406 Jun 17 22:58 __CGIDIR__/BackupPC_Admin
1175 The setuid script won't work unless perl on your machine was installed
1176 with setuid emulation. This is likely the problem if you get an error
1177 saying such as "Wrong user: my userid is 25, instead of 150", meaning
1178 the script is running as the httpd user, not the BackupPC user.
1179 This is because setuid scripts are disabled by the kernel in most
1180 flavors of unix and linux.
1182 To see if your perl has setuid emulation, see if there is a program
1183 called sperl5.6.0 (or sperl5.8.2 etc, based on your perl version)
1184 in the place where perl is installed. If you can't find this program,
1185 then you have two options: rebuild and reinstall perl with the setuid
1186 emulation turned on (answer "y" to the question "Do you want to do
1187 setuid/setgid emulation?" when you run perl's configure script), or
1188 switch to the mod_perl alternative for the CGI script (which doesn't
1189 need setuid to work).
1191 =item Mod_perl Setup
1193 The advantage of the mod_perl setup is that no setuid script is needed,
1194 and there is a huge performance advantage. Not only does all the perl
1195 code need to be parsed just once, the config.pl and hosts files, plus
1196 the connection to the BackupPC server are cached between requests. The
1197 typical speedup is around 15 times.
1199 To use mod_perl you need to run Apache as user __BACKUPPCUSER__.
1200 If you need to run multiple Apache's for different services then
1201 you need to create multiple top-level Apache directories, each
1202 with their own config file. You can make copies of /etc/init.d/httpd
1203 and use the -d option to httpd to point each http to a different
1204 top-level directory. Or you can use the -f option to explicitly
1205 point to the config file. Multiple Apache's will run on different
1206 Ports (eg: 80 is standard, 8080 is a typical alternative port accessed
1207 via http://yourhost.com:8080).
1209 Inside BackupPC's Apache http.conf file you should check the
1210 settings for ServerRoot, DocumentRoot, User, Group, and Port. See
1211 L<http://httpd.apache.org/docs/server-wide.html> for more details.
1213 For mod_perl, BackupPC_Admin should not have setuid permission, so
1214 you should turn it off:
1216 chmod u-s __CGIDIR__/BackupPC_Admin
1218 To tell Apache to use mod_perl to execute BackupPC_Admin, add this
1219 to Apache's 1.x httpd.conf file:
1221 <IfModule mod_perl.c>
1222 PerlModule Apache::Registry
1224 <Location /cgi-bin/BackupPC/BackupPC_Admin> # <--- change path as needed
1225 SetHandler perl-script
1226 PerlHandler Apache::Registry
1232 Apache 2.0.44 with Perl 5.8.0 on RedHat 7.1, Don Silvia reports that
1233 this works (with tweaks from Michael Tuzi):
1235 LoadModule perl_module modules/mod_perl.so
1238 <Directory /path/to/cgi/>
1239 SetHandler perl-script
1240 PerlResponseHandler ModPerl::Registry
1241 PerlOptions +ParseHeaders
1245 Allow from 192.168.0
1246 AuthName "Backup Admin"
1248 AuthUserFile /path/to/user_file
1252 There are other optimizations and options with mod_perl. For
1253 example, you can tell mod_perl to preload various perl modules,
1254 which saves memory compared to loading separate copies in every
1255 Apache process after they are forked. See Stas's definitive
1256 mod_perl guide at L<http://perl.apache.org/guide>.
1260 BackupPC_Admin requires that users are authenticated by Apache.
1261 Specifically, it expects that Apache sets the REMOTE_USER environment
1262 variable when it runs. There are several ways to do this. One way
1263 is to create a .htaccess file in the cgi-bin directory that looks like:
1265 AuthGroupFile /etc/httpd/conf/group # <--- change path as needed
1266 AuthUserFile /etc/http/conf/passwd # <--- change path as needed
1271 You will also need "AllowOverride Indexes AuthConfig" in the Apache
1272 httpd.conf file to enable the .htaccess file. Alternatively, everything
1273 can go in the Apache httpd.conf file inside a Location directive. The
1274 list of users and password file above can be extracted from the NIS
1277 One alternative is to use LDAP. In Apache's http.conf add these lines:
1279 LoadModule auth_ldap_module modules/auth_ldap.so
1280 AddModule auth_ldap.c
1282 # cgi-bin - auth via LDAP (for BackupPC)
1283 <Location /cgi-binBackupPC/BackupPC_Admin> # <--- change path as needed
1285 AuthName "BackupPC login"
1286 # replace MYDOMAIN, PORT, ORG and CO as needed
1287 AuthLDAPURL ldap://ldap.MYDOMAIN.com:PORT/o=ORG,c=CO?uid?sub?(objectClass=*)
1291 If you want to disable the user authentication you can set
1292 $Conf{CgiAdminUsers} to '*', which allows any user to have
1293 full access to all hosts and backups. In this case the REMOTE_USER
1294 environment variable does not have to be set by Apache.
1296 Alternatively, you can force a particular user name by getting Apache
1297 to set REMOTE_USER, eg, to hardcode the user to www you could add
1298 this to Apache's httpd.conf:
1300 <Location /cgi-bin/BackupPC/BackupPC_Admin> # <--- change path as needed
1301 Setenv REMOTE_USER www
1304 Finally, you should also edit the config.pl file and adjust, as necessary,
1305 the CGI-specific settings. They're near the end of the config file. In
1306 particular, you should specify which users or groups have administrator
1307 (privileged) access: see the config settings $Conf{CgiAdminUserGroup}
1308 and $Conf{CgiAdminUsers}. Also, the configure.pl script placed various
1309 images into $Conf{CgiImageDir} that BackupPC_Admin needs to serve
1310 up. You should make sure that $Conf{CgiImageDirURL} is the correct
1311 URL for the image directory.
1313 See the section L<Fixing installation problems|fixing installation problems> for suggestions on debugging the Apache authentication setup.
1315 =head2 How BackupPC Finds Hosts
1317 Starting with v2.0.0 the way hosts are discovered has changed. In most
1318 cases you should specify 0 for the DHCP flag in the conf/hosts file,
1319 even if the host has a dynamically assigned IP address.
1321 BackupPC (starting with v2.0.0) looks up hosts with DHCP = 0 in this manner:
1327 First DNS is used to lookup the IP address given the client's name
1328 using perl's gethostbyname() function. This should succeed for machines
1329 that have fixed IP addresses that are known via DNS. You can manually
1330 see whether a given host have a DNS entry according to perls'
1331 gethostbyname function with this command:
1333 perl -e 'print(gethostbyname("myhost") ? "ok\n" : "not found\n");'
1337 If gethostbyname() fails, BackupPC then attempts a NetBios multicast to
1338 find the host. Provided your client machine is configured properly,
1339 it should respond to this NetBios multicast request. Specifically,
1340 BackupPC runs a command of this form:
1344 If this fails you will see output like:
1346 querying myhost on 10.10.255.255
1347 name_query failed to find name myhost
1349 If this success you will see output like:
1351 querying myhost on 10.10.255.255
1352 10.10.1.73 myhost<00>
1354 Depending on your netmask you might need to specify the -B option to
1355 nmblookup. For example:
1357 nmblookup -B 10.10.1.255 myhost
1359 If necessary, experiment on the nmblookup command that will return the
1360 IP address of the client given its name. Then update
1361 $Conf{NmbLookupFindHostCmd} with any necessary options to nmblookup.
1365 For hosts that have the DHCP flag set to 1, these machines are
1366 discovered as follows:
1372 A DHCP address pool ($Conf{DHCPAddressRanges}) needs to be specified.
1373 BackupPC will check the NetBIOS name of each machine in the range using
1374 a command of the form:
1376 nmblookup -A W.X.Y.Z
1378 where W.X.Y.Z is each candidate address from $Conf{DHCPAddressRanges}.
1379 Any host that has a valid NetBIOS name returned by this command (ie:
1380 matching an entry in the hosts file) will be backed up. You can
1381 modify the specific nmblookup command if necessary via $Conf{NmbLookupCmd}.
1385 You only need to use this DHCP feature if your client machine doesn't
1386 respond to the NetBios multicast request:
1390 but does respond to a request directed to its IP address:
1392 nmblookup -A W.X.Y.Z
1396 =head2 Other installation topics
1400 =item Removing a client
1402 If there is a machine that no longer needs to be backed up (eg: a retired
1403 machine) you have two choices. First, you can keep the backups accessible
1404 and browsable, but disable all new backups. Alternatively, you can
1405 completely remove the client and all its backups.
1407 To disable backups for a client there are two special values for
1408 $Conf{FullPeriod} in that client's per-PC config.pl file:
1414 Don't do any regular backups on this machine. Manually
1415 requested backups (via the CGI interface) will still occur.
1419 Don't do any backups on this machine. Manually requested
1420 backups (via the CGI interface) will be ignored.
1424 This will still allow that client's old backups to be browsable
1427 To completely remove a client and all its backups, you should remove its
1428 entry in the conf/hosts file, and then delete the __TOPDIR__/pc/$host
1429 directory. Whenever you change the hosts file, you should send
1430 BackupPC a HUP (-1) signal so that it re-reads the hosts file.
1431 If you don't do this, BackupPC will automatically re-read the
1432 hosts file at the next regular wakeup.
1434 Note that when you remove a client's backups you won't initially recover
1435 a lot of disk space. That's because the client's files are still in
1436 the pool. Overnight, when BackupPC_nightly next runs, all the unused
1437 pool files will be deleted and this will recover the disk space used
1438 by the client's backups.
1440 =item Copying the pool
1442 If the pool disk requirements grow you might need to copy the entire
1443 data directory to a new (bigger) file system. Hopefully you are lucky
1444 enough to avoid this by having the data directory on a RAID file system
1445 or LVM that allows the capacity to be grown in place by adding disks.
1447 The backup data directories contain large numbers of hardlinks. If
1448 you try to copy the pool the target directory will occupy a lot more
1449 space if the hardlinks aren't re-established.
1451 The best way to copy a pool file system, if possible, is by copying
1452 the raw device at the block level (eg: using dd). Application level
1453 programs that understand hardlinks include the GNU cp program with
1454 the -a option and rsync -H. However, the large number of hardlinks
1455 in the pool will make the memory usage large and the copy very slow.
1456 Don't forget to stop BackupPC while the copy runs.
1460 =head2 Fixing installation problems
1462 Please see the FAQ at L<http://backuppc.sourceforge.net/faq> for
1463 debugging suggestions.
1465 =head1 Restore functions
1467 BackupPC supports several different methods for restoring files. The
1468 most convenient restore options are provided via the CGI interface.
1469 Alternatively, backup files can be restored using manual commands.
1471 =head2 CGI restore options
1473 By selecting a host in the CGI interface, a list of all the backups
1474 for that machine will be displayed. By selecting the backup number
1475 you can navigate the shares and directory tree for that backup.
1477 BackupPC's CGI interface automatically fills incremental backups
1478 with the corresponding full backup, which means each backup has
1479 a filled appearance. Therefore, there is no need to do multiple
1480 restores from the incremental and full backups: BackupPC does all
1481 the hard work for you. You simply select the files and directories
1482 you want from the correct backup vintage in one step.
1484 You can download a single backup file at any time simply by selecting
1485 it. Your browser should prompt you with the file name and ask you
1486 whether to open the file or save it to disk.
1488 Alternatively, you can select one or more files or directories in
1489 the currently selected directory and select "Restore selected files".
1490 (If you need to restore selected files and directories from several
1491 different parent directories you will need to do that in multiple
1494 If you select all the files in a directory, BackupPC will replace
1495 the list of files with the parent directory. You will be presented
1496 with a screen that has three options:
1500 =item Option 1: Direct Restore
1502 With this option the selected files and directories are restored
1503 directly back onto the host, by default in their original location.
1504 Any old files with the same name will be overwritten, so use caution.
1505 You can optionally change the target host name, target share name,
1506 and target path prefix for the restore, allowing you to restore the
1507 files to a different location.
1509 Once you select "Start Restore" you will be prompted one last time
1510 with a summary of the exact source and target files and directories
1511 before you commit. When you give the final go ahead the restore
1512 operation will be queued like a normal backup job, meaning that it
1513 will be deferred if there is a backup currently running for that host.
1514 When the restore job is run, smbclient, tar, rsync or rsyncd is used
1515 (depending upon $Conf{XferMethod}) to actually restore the files.
1516 Sorry, there is currently no option to cancel a restore that has been
1519 A record of the restore request, including the result and list of
1520 files and directories, is kept. It can be browsed from the host's
1521 home page. $Conf{RestoreInfoKeepCnt} specifies how many old restore
1522 status files to keep.
1524 Note that for direct restore to work, the $Conf{XferMethod} must
1525 be able to write to the client. For example, that means an SMB
1526 share for smbclient needs to be writable, and the rsyncd module
1527 needs "read only" set to "false". This creates additional security
1528 risks. If you only create read-only SMB shares (which is a good
1529 idea), then the direct restore will fail. You can disable the
1530 direct restore option by setting $Conf{SmbClientRestoreCmd},
1531 $Conf{TarClientRestoreCmd} and $Conf{RsyncRestoreArgs} to undef.
1533 =item Option 2: Download Zip archive
1535 With this option a zip file containing the selected files and directories
1536 is downloaded. The zip file can then be unpacked or individual files
1537 extracted as necessary on the host machine. The compression level can be
1538 specified. A value of 0 turns off compression.
1540 When you select "Download Zip File" you should be prompted where to
1541 save the restore.zip file.
1543 BackupPC does not consider downloading a zip file as an actual
1544 restore operation, so the details are not saved for later browsing
1545 as in the first case. However, a mention that a zip file was
1546 downloaded by a particular user, and a list of the files, does
1547 appear in BackupPC's log file.
1549 =item Option 3: Download Tar archive
1551 This is identical to the previous option, except a tar file is downloaded
1552 rather than a zip file (and there is currently no compression option).
1556 =head2 Command-line restore options
1558 Apart from the CGI interface, BackupPC allows you to restore files
1559 and directories from the command line. The following programs can
1566 For each file name argument it inflates (uncompresses) the file and
1567 writes it to stdout. To use BackupPC_zcat you could give it the
1570 __INSTALLDIR__/bin/BackupPC_zcat __TOPDIR__/pc/host/5/fc/fcraig/fexample.txt > example.txt
1572 It's your responsibility to make sure the file is really compressed:
1573 BackupPC_zcat doesn't check which backup the requested file is from.
1574 BackupPC_zcat returns a non-zero status if it fails to uncompress
1577 =item BackupPC_tarCreate
1579 BackupPC_tarCreate creates a tar file for any files or directories in
1580 a particular backup. Merging of incrementals is done automatically,
1581 so you don't need to worry about whether certain files appear in the
1582 incremental or full backup.
1586 BackupPC_tarCreate [-t] [-h host] [-n dumpNum] [-s shareName]
1587 [-r pathRemove] [-p pathAdd] [-b BLOCKS] [-w writeBufSz]
1588 files/directories...
1590 The command-line files and directories are relative to the specified
1591 shareName. The tar file is written to stdout.
1593 The required options are:
1599 host from which the tar archive is created
1603 dump number from which the tar archive is created
1607 share name from which the tar archive is created
1617 print summary totals
1621 path prefix that will be replaced with pathAdd
1629 the tar block size, default is 20, meaning tar writes data in 20 * 512
1634 write buffer size, default 1048576 (1MB). You can increase this if
1635 you are trying to stream to a fast tape device.
1639 The -h, -n and -s options specify which dump is used to generate
1640 the tar archive. The -r and -p options can be used to relocate
1641 the paths in the tar archive so extracted files can be placed
1642 in a location different from their original location.
1644 =item BackupPC_zipCreate
1646 BackupPC_zipCreate creates a zip file for any files or directories in
1647 a particular backup. Merging of incrementals is done automatically,
1648 so you don't need to worry about whether certain files appear in the
1649 incremental or full backup.
1653 BackupPC_zipCreate [-t] [-h host] [-n dumpNum] [-s shareName]
1654 [-r pathRemove] [-p pathAdd] [-c compressionLevel]
1655 files/directories...
1657 The command-line files and directories are relative to the specified
1658 shareName. The zip file is written to stdout.
1660 The required options are:
1666 host from which the zip archive is created
1670 dump number from which the zip archive is created
1674 share name from which the zip archive is created
1684 print summary totals
1688 path prefix that will be replaced with pathAdd
1696 compression level (default is 0, no compression)
1700 The -h, -n and -s options specify which dump is used to generate
1701 the zip archive. The -r and -p options can be used to relocate
1702 the paths in the zip archive so extracted files can be placed
1703 in a location different from their original location.
1707 Each of these programs reside in __INSTALLDIR__/bin.
1709 =head1 Archive functions
1711 BackupPC supports archiving to removable media. For users that require
1712 offsite backups, BackupPC can create archives that stream to tape
1713 devices, or create files of specified sizes to fit onto cd or dvd media.
1715 Each archive type is specified by a BackupPC host with its XferMethod
1716 set to 'archive'. This allows for multiple configurations at sites where
1717 there might be a combination of tape and cd/dvd backups being made.
1719 BackupPC provides a menu that allows one or more hosts to be archived.
1720 The most recent backup of each host is archived using BackupPC_tarCreate,
1721 and the output is optionally compressed and split into fixed-sized
1724 The archive for each host is done by default using
1725 __INSTALLDIR__/BackupPC_archiveHost. This script can be copied
1726 and customized as needed.
1728 =head2 Configuring an Archive Host
1730 To create an Archive Host, add it to the hosts file just as any other host
1731 and call it a name that best describes the type of archive, e.g. ArchiveDLT
1733 To tell BackupPC that the Host is for Archives, create a config.pl file in
1734 the Archive Hosts's pc directory, adding the following line:
1736 $Conf{XferMethod} = 'archive';
1738 To further customise the archive's parameters you can adding the changed
1739 parameters in the host's config.pl file. The parameters are explained in
1740 the config.pl file. Parameters may be fixed or the user can be allowed
1741 to change them (eg: output device).
1743 The per-host archive command is $Conf{ArchiveClientCmd}. By default
1746 __INSTALLDIR__/BackupPC_archiveHost
1748 which you can copy and customize as necessary.
1750 =head2 Starting an Archive
1752 In the web interface, click on the Archive Host you wish to use. You will see a
1753 list of previous archives and a summary on each. By clicking the "Start Archive"
1754 button you are presented with the list of hosts and the approximate backup size
1755 (note this is raw size, not projected compressed size) Select the hosts you wish
1756 to archive and press the "Archive Selected Hosts" button.
1758 The next screen allows you to adjust the parameters for this archive run.
1759 Press the "Start the Archive" to start archiving the selected hosts with the
1760 parameters displayed.
1762 =head1 Other CGI Functions
1764 =head2 Configuration and Host Editor
1766 The CGI interface has a complete configuration and host editor.
1767 Only the administrator can edit the main configuration settings
1768 and hosts. The edit links are in the left navigation bar.
1770 When changes are made to any parameter a "Save" button appears
1771 at the top of the page. If you are editing a text box you will
1772 need to click outside of the text box to make the Save button
1773 appear. If you don't select Save then the changes won't be saved.
1775 The host-specific configuration can be edited from the host
1776 summary page using the link in the left navigation bar.
1777 The administrator can edit any of the host-specific
1778 configuration settings.
1780 When editing the host-specific configuration, each parameter has
1781 an "override" setting that denotes the value is host-specific,
1782 meaning that it overrides the setting in the main configuration.
1783 If you unselect "override" then the setting is removed from
1784 the host-specific configuration, and the main configuration
1787 User's can edit their host-specific configuration if enabled
1788 via $Conf{CgiUserConfigEditEnable}. The specific subset
1789 of configuration settings that a user can edit is specified
1790 with $Conf{CgiUserConfigEdit}. It is recommended to make this
1791 list short as possible (you probably don't want your users saving
1792 dozens of backups) and it is essential that they can't edit any
1793 of the Cmd configuration settings, otherwise they can specify
1794 an arbitrary command that will be executed as the BackupPC
1799 BackupPC supports a very basic RSS feed. Provided you have the
1800 XML::RSS perl module installed, a URL simular to this will
1801 provide RSS information:
1803 http://localhost/cgi-bin/BackupPC/BackupPC_Admin?action=rss
1805 This feature is experimental. The information included will
1808 =head1 BackupPC Design
1810 =head2 Some design issues
1814 =item Pooling common files
1816 To quickly see if a file is already in the pool, an MD5 digest of the
1817 file length and contents is used as the file name in the pool. This
1818 can't guarantee a file is identical: it just reduces the search to
1819 often a single file or handful of files. A complete file comparison
1820 is always done to verify if two files are really the same.
1822 Identical files on multiples backups are represented by hard links.
1823 Hardlinks are used so that identical files all refer to the same
1824 physical file on the server's disk. Also, hard links maintain
1825 reference counts so that BackupPC knows when to delete unused files
1828 For the computer-science majors among you, you can think of the pooling
1829 system used by BackupPC as just a chained hash table stored on a (big)
1832 =item The hashing function
1834 There is a tradeoff between how much of file is used for the MD5 digest
1835 and the time taken comparing all the files that have the same hash.
1837 Using the file length and just the first 4096 bytes of the file for the
1838 MD5 digest produces some repetitions. One example: with 900,000 unique
1839 files in the pool, this hash gives about 7,000 repeated files, and in
1840 the worst case 500 files have the same hash. That's not bad: we only
1841 have to do a single file compare 99.2% of the time. But in the worst
1842 case we have to compare as many as 500 files checking for a match.
1844 With a modest increase in CPU time, if we use the file length and the
1845 first 256K of the file we now only have 500 repeated files and in the
1846 worst case around 20 files have the same hash. Furthermore, if we
1847 instead use the first and last 128K of the file (more specifically, the
1848 first and eighth 128K chunks for files larger than 1MB) we get only 300
1849 repeated files and in the worst case around 20 files have the same hash.
1851 Based on this experimentation, this is the hash function used by BackupPC.
1852 It is important that you don't change the hash function after files
1853 are already in the pool. Otherwise your pool will grow to twice the
1854 size until all the old backups (and all the old files with old hashes)
1859 BackupPC supports compression. It uses the deflate and inflate methods
1860 in the Compress::Zlib module, which is based on the zlib compression
1861 library (see L<http://www.gzip.org/zlib/>).
1863 The $Conf{CompressLevel} setting specifies the compression level to use.
1864 Zero (0) means no compression. Compression levels can be from 1 (least
1865 cpu time, slightly worse compression) to 9 (most cpu time, slightly
1866 better compression). The recommended value is 3. Changing it to 5, for
1867 example, will take maybe 20% more cpu time and will get another 2-3%
1868 additional compression. Diminishing returns set in above 5. See the zlib
1869 documentation for more information about compression levels.
1871 BackupPC implements compression with minimal CPU load. Rather than
1872 compressing every incoming backup file and then trying to match it
1873 against the pool, BackupPC computes the MD5 digest based on the
1874 uncompressed file, and matches against the candidate pool files by
1875 comparing each uncompressed pool file against the incoming backup file.
1876 Since inflating a file takes roughly a factor of 10 less CPU time than
1877 deflating there is a big saving in CPU time.
1879 The combination of pooling common files and compression can yield
1880 a factor of 8 or more overall saving in backup storage.
1884 =head2 BackupPC operation
1886 BackupPC reads the configuration information from
1887 __CONFDIR__/config.pl. It then runs and manages all the backup
1888 activity. It maintains queues of pending backup requests, user backup
1889 requests and administrative commands. Based on the configuration various
1890 requests will be executed simultaneously.
1892 As specified by $Conf{WakeupSchedule}, BackupPC wakes up periodically
1893 to queue backups on all the PCs. This is a four step process:
1899 For each host and DHCP address backup requests are queued on the
1900 background command queue.
1904 For each PC, BackupPC_dump is forked. Several of these may be run in
1905 parallel, based on the configuration. First a ping is done to see if
1906 the machine is alive. If this is a DHCP address, nmblookup is run to
1907 get the netbios name, which is used as the host name. If DNS lookup
1908 fails, $Conf{NmbLookupFindHostCmd} is run to find the IP address from
1909 the host name. The file __TOPDIR__/pc/$host/backups is read to decide
1910 whether a full or incremental backup needs to be run. If no backup is
1911 scheduled, or the ping to $host fails, then BackupPC_dump exits.
1913 The backup is done using the specified XferMethod. Either samba's smbclient
1914 or tar over ssh/rsh/nfs piped into BackupPC_tarExtract, or rsync over ssh/rsh
1915 is run, or rsyncd is connected to, with the incoming data
1916 extracted to __TOPDIR__/pc/$host/new. The XferMethod output is put
1917 into __TOPDIR__/pc/$host/XferLOG.
1919 The letter in the XferLOG file shows the type of object, similar to the
1920 first letter of the modes displayed by ls -l:
1924 b -> block special file
1925 c -> character special file
1926 p -> pipe file (fifo)
1927 nothing -> regular file
1935 new for this backup (ie: directory or file not in pool)
1939 found a match in the pool
1943 file is identical to previous backup (contents were
1944 checksummed and verified during full dump).
1948 file skipped in incremental because attributes are the
1949 same (only displayed if $Conf{XferLogLevel} >= 2).
1953 As BackupPC_tarExtract extracts the files from smbclient or tar, or as
1954 rsync runs, it checks each file in the backup to see if it is identical
1955 to an existing file from any previous backup of any PC. It does this
1956 without needed to write the file to disk. If the file matches an
1957 existing file, a hardlink is created to the existing file in the pool.
1958 If the file does not match any existing files, the file is written to
1959 disk and the file name is saved in __TOPDIR__/pc/$host/NewFileList for
1960 later processing by BackupPC_link. BackupPC_tarExtract and rsync can handle
1961 arbitrarily large files and multiple candidate matching files without
1962 needing to write the file to disk in the case of a match. This
1963 significantly reduces disk writes (and also reads, since the pool file
1964 comparison is done disk to memory, rather than disk to disk).
1966 Based on the configuration settings, BackupPC_dump checks each
1967 old backup to see if any should be removed. Any expired backups
1968 are moved to __TOPDIR__/trash for later removal by BackupPC_trashClean.
1972 For each complete, good, backup, BackupPC_link is run.
1973 To avoid race conditions as new files are linked into the
1974 pool area, only a single BackupPC_link program runs
1975 at a time and the rest are queued.
1977 BackupPC_link reads the NewFileList written by BackupPC_dump and
1978 inspects each new file in the backup. It re-checks if there is a
1979 matching file in the pool (another BackupPC_link
1980 could have added the file since BackupPC_dump checked). If so, the file
1981 is removed and replaced by a hard link to the existing file. If the file
1982 is new, a hard link to the file is made in the pool area, so that this
1983 file is available for checking against each new file and new backup.
1985 Then, if $Conf{IncrFill} is set (note that the default setting is
1986 off), for each incremental backup, hard links are made in the new
1987 backup to all files that were not extracted during the incremental
1988 backups. The means the incremental backup looks like a complete
1989 image of the PC (with the exception that files that were removed on
1990 the PC since the last full backup will still appear in the backup
1993 The CGI interface knows how to merge unfilled incremental backups will
1994 the most recent prior filled (full) backup, giving the incremental
1995 backups a filled appearance. The default for $Conf{IncrFill} is off,
1996 since there is no need to fill incremental backups. This saves
1997 some level of disk activity, since lots of extra hardlinks are no
1998 longer needed (and don't have to be deleted when the backup expires).
2002 BackupPC_trashClean is always run in the background to remove any
2003 expired backups. Every 5 minutes it wakes up and removes all the files
2004 in __TOPDIR__/trash.
2006 Also, once each night, BackupPC_nightly is run to complete some
2007 additional administrative tasks, such as cleaning the pool. This
2008 involves removing any files in the pool that only have a single
2009 hard link (meaning no backups are using that file). Again, to
2010 avoid race conditions, BackupPC_nightly is only run when there
2011 are no BackupPC_link processes running. When BackupPC_nightly is
2012 run no new BackupPC_link jobs are started. If BackupPC_nightly
2013 takes too long to run, the settings $Conf{MaxBackupPCNightlyJobs}
2014 and $Conf{BackupPCNightlyPeriod} can be used to run several
2015 BackupPC_nightly processes in parallel, and to split its job over
2020 BackupPC also listens for TCP connections on $Conf{ServerPort}, which
2021 is used by the CGI script BackupPC_Admin for status reporting and
2022 user-initiated backup or backup cancel requests.
2024 =head2 Storage layout
2026 BackupPC resides in several directories:
2030 =item __INSTALLDIR__
2032 Perl scripts comprising BackupPC reside in __INSTALLDIR__/bin,
2033 libraries are in __INSTALLDIR__/lib and documentation
2034 is in __INSTALLDIR__/doc.
2038 The CGI script BackupPC_Admin resides in this cgi binary directory.
2042 All the configuration information resides below __CONFDIR__.
2043 This directory contains:
2045 The directory __CONFDIR__ contains:
2051 Configuration file. See L<Configuration file|configuration file>
2052 below for more details.
2056 Hosts file, which lists all the PCs to backup.
2060 The directory __CONFDIR__/pc contains per-client configuration files
2061 that override settings in the main configuration file. Each file
2062 is named __CONFDIR__/pc/HOST.pl, where HOST is the host name.
2064 In pre-FHS versions of BackupPC these files were located in
2065 __TOPDIR__/pc/HOST/config.pl.
2071 The directory __LOGDIR__ (__TOPDIR__/log on pre-FHS versions
2072 of BackupPC) contains:
2078 Current (today's) log file output from BackupPC.
2080 =item LOG.0 or LOG.0.z
2082 Yesterday's log file output. Log files are aged daily and compressed
2083 (if compression is enabled), and old LOG files are deleted.
2087 Contains BackupPC's process id.
2091 A summary of BackupPC's status written periodically by BackupPC so
2092 that certain state information can be maintained if BackupPC is
2093 restarted. Should not be edited.
2095 =item UserEmailInfo.pl
2097 A summary of what email was last sent to each user, and when the
2098 last email was sent. Should not be edited.
2104 All of BackupPC's data (PC backup images, logs, configuration information)
2105 is stored below this directory.
2109 Below __TOPDIR__ are several directories:
2113 =item __TOPDIR__/trash
2115 Any directories and files below this directory are periodically deleted
2116 whenever BackupPC_trashClean checks. When a backup is aborted or when an
2117 old backup expires, BackupPC_dump simply moves the directory to
2118 __TOPDIR__/trash for later removal by BackupPC_trashClean.
2120 =item __TOPDIR__/pool
2122 All uncompressed files from PC backups are stored below __TOPDIR__/pool.
2123 Each file's name is based on the MD5 hex digest of the file contents.
2124 Specifically, for files less than 256K, the file length and the entire
2125 file is used. For files up to 1MB, the file length and the first and
2126 last 128K are used. Finally, for files longer than 1MB, the file length,
2127 and the first and eighth 128K chunks for the file are used.
2129 Each file is stored in a subdirectory X/Y/Z, where X, Y, Z are the
2130 first 3 hex digits of the MD5 digest.
2132 For example, if a file has an MD5 digest of 123456789abcdef0,
2133 the file is stored in __TOPDIR__/pool/1/2/3/123456789abcdef0.
2135 The MD5 digest might not be unique (especially since not all the file's
2136 contents are used for files bigger than 256K). Different files that have
2137 the same MD5 digest are stored with a trailing suffix "_n" where n is
2138 an incrementing number starting at 0. So, for example, if two additional
2139 files were identical to the first, except the last byte was different,
2140 and assuming the file was larger than 1MB (so the MD5 digests are the
2141 same but the files are actually different), the three files would be
2144 __TOPDIR__/pool/1/2/3/123456789abcdef0
2145 __TOPDIR__/pool/1/2/3/123456789abcdef0_0
2146 __TOPDIR__/pool/1/2/3/123456789abcdef0_1
2148 Both BackupPC_dump (actually, BackupPC_tarExtract) and BackupPC_link are
2149 responsible for checking newly backed up files against the pool. For
2150 each file, the MD5 digest is used to generate a file name in the pool
2151 directory. If the file exists in the pool, the contents are compared.
2152 If there is no match, additional files ending in "_n" are checked.
2153 (Actually, BackupPC_tarExtract compares multiple candidate files in
2154 parallel.) If the file contents exactly match, the file is created by
2155 simply making a hard link to the pool file (this is done by
2156 BackupPC_tarExtract as the backup proceeds). Otherwise,
2157 BackupPC_tarExtract writes the new file to disk and a new hard link is
2158 made in the pool to the file (this is done later by BackupPC_link).
2160 Therefore, every file in the pool will have at least 2 hard links
2161 (one for the pool file and one for the backup file below __TOPDIR__/pc).
2162 Identical files from different backups or PCs will all be linked to
2163 the same file. When old backups are deleted, some files in the pool
2164 might only have one link. BackupPC_nightly checks the entire pool
2165 and removes all files that have only a single link, thereby recovering
2166 the storage for that file.
2168 One other issue: zero length files are not pooled, since there are a lot
2169 of these files and on most file systems it doesn't save any disk space
2170 to turn these files into hard links.
2172 =item __TOPDIR__/cpool
2174 All compressed files from PC backups are stored below __TOPDIR__/cpool.
2175 Its layout is the same as __TOPDIR__/pool, and the hashing function
2176 is the same (and, importantly, based on the uncompressed file, not
2177 the compressed file).
2179 =item __TOPDIR__/pc/$host
2181 For each PC $host, all the backups for that PC are stored below
2182 the directory __TOPDIR__/pc/$host. This directory contains the
2189 Current log file for this PC from BackupPC_dump.
2191 =item LOG.DDMMYYYY or LOG.DDMMYYYY.z
2193 Last month's log file. Log files are aged monthly and compressed
2194 (if compression is enabled), and old LOG files are deleted.
2195 In earlier versions of BackupPC these files used to have
2196 a suffix of 0, 1, ....
2198 =item XferERR or XferERR.z
2200 Output from the transport program (ie: smbclient, tar or rsync)
2201 for the most recent failed backup.
2205 Subdirectory in which the current backup is stored. This
2206 directory is renamed if the backup succeeds.
2208 =item XferLOG or XferLOG.z
2210 Output from the transport program (ie: smbclient, tar or rsync)
2211 for the current backup.
2213 =item nnn (an integer)
2215 Successful backups are in directories numbered sequentially starting at 0.
2217 =item XferLOG.nnn or XferLOG.nnn.z
2219 Output from the transport program (ie: smbclient, tar or rsync)
2220 corresponding to backup number nnn.
2222 =item RestoreInfo.nnn
2224 Information about restore request #nnn including who, what, when, and
2225 why. This file is in Data::Dumper format. (Note that the restore
2226 numbers are not related to the backup number.)
2228 =item RestoreLOG.nnn.z
2230 Output from smbclient, tar or rsync during restore #nnn. (Note that the restore
2231 numbers are not related to the backup number.)
2233 =item ArchiveInfo.nnn
2235 Information about archive request #nnn including who, what, when, and
2236 why. This file is in Data::Dumper format. (Note that the archive
2237 numbers are not related to the restore or backup number.)
2239 =item ArchiveLOG.nnn.z
2241 Output from archive #nnn. (Note that the archive numbers are not related
2242 to the backup or restore number.)
2246 Old location of optional configuration settings specific to this host.
2247 Settings in this file override the main configuration file.
2248 In new versions of BackupPC the per-host configuration files are
2249 stored in __CONFDIR__/pc/HOST.pl.
2253 A tab-delimited ascii table listing information about each successful
2254 backup, one per row. The columns are:
2260 The backup number, an integer that starts at 0 and increments
2261 for each successive backup. The corresponding backup is stored
2262 in the directory num (eg: if this field is 5, then the backup is
2263 stored in __TOPDIR__/pc/$host/5).
2267 Set to "full" or "incr" for full or incremental backup.
2271 Start time of the backup in unix seconds.
2275 Stop time of the backup in unix seconds.
2279 Number of files backed up (as reported by smbclient, tar or rsync).
2283 Total file size backed up (as reported by smbclient, tar or rsync).
2287 Number of files that were already in the pool
2288 (as determined by BackupPC_dump and BackupPC_link).
2292 Total size of files that were already in the pool
2293 (as determined by BackupPC_dump and BackupPC_link).
2297 Number of files that were not in the pool
2298 (as determined by BackupPC_link).
2302 Total size of files that were not in the pool
2303 (as determined by BackupPC_link).
2307 Number of errors or warnings from smbclient, tar or rsync.
2311 Number of errors from smbclient that were bad file errors (zero otherwise).
2315 Number of errors from smbclient that were bad share errors (zero otherwise).
2319 Number of errors from BackupPC_tarExtract.
2323 The compression level used on this backup. Zero or empty means no
2328 Total compressed size of files that were already in the pool
2329 (as determined by BackupPC_dump and BackupPC_link).
2333 Total compressed size of files that were not in the pool
2334 (as determined by BackupPC_link).
2338 Set if this backup has not been filled in with the most recent
2339 previous filled or full backup. See $Conf{IncrFill}.
2343 If this backup was filled (ie: noFill is 0) then this is the
2344 number of the backup that it was filled from
2348 Set if this backup has mangled file names and attributes. Always
2349 true for backups in v1.4.0 and above. False for all backups prior
2354 Set to the value of $Conf{XferMethod} when this dump was done.
2358 The level of this dump. A full dump is level 0. Currently incrementals
2359 are 1. But when multi-level incrementals are supported this will reflect
2360 each dump's incremental level.
2366 A tab-delimited ascii table listing information about each requested
2367 restore, one per row. The columns are:
2373 Restore number (matches the suffix of the RestoreInfo.nnn and
2374 RestoreLOG.nnn.z file), unrelated to the backup number.
2378 Start time of the restore in unix seconds.
2382 End time of the restore in unix seconds.
2386 Result (ok or failed).
2390 Error message if restore failed.
2394 Number of files restored.
2398 Size in bytes of the restored files.
2402 Number of errors from BackupPC_tarCreate during restore.
2406 Number of errors from smbclient, tar or rsync during restore.
2412 A tab-delimited ascii table listing information about each requested
2413 archive, one per row. The columns are:
2419 Archive number (matches the suffix of the ArchiveInfo.nnn and
2420 ArchiveLOG.nnn.z file), unrelated to the backup or restore number.
2424 Start time of the restore in unix seconds.
2428 End time of the restore in unix seconds.
2432 Result (ok or failed).
2436 Error message if archive failed.
2444 =head2 Compressed file format
2446 The compressed file format is as generated by Compress::Zlib::deflate
2447 with one minor, but important, tweak. Since Compress::Zlib::inflate
2448 fully inflates its argument in memory, it could take large amounts of
2449 memory if it was inflating a highly compressed file. For example, a
2450 200MB file of 0x0 bytes compresses to around 200K bytes. If
2451 Compress::Zlib::inflate was called with this single 200K buffer, it
2452 would need to allocate 200MB of memory to return the result.
2454 BackupPC watches how efficiently a file is compressing. If a big file
2455 has very high compression (meaning it will use too much memory when it
2456 is inflated), BackupPC calls the flush() method, which gracefully
2457 completes the current compression. BackupPC then starts another
2458 deflate and simply appends the output file. So the BackupPC compressed
2459 file format is one or more concatenated deflations/flushes. The specific
2460 ratios that BackupPC uses is that if a 6MB chunk compresses to less
2461 than 64K then a flush will be done.
2463 Back to the example of the 200MB file of 0x0 bytes. Adding flushes
2464 every 6MB adds only 200 or so bytes to the 200K output. So the
2465 storage cost of flushing is negligible.
2467 To easily decompress a BackupPC compressed file, the script
2468 BackupPC_zcat can be found in __INSTALLDIR__/bin. For each
2469 file name argument it inflates the file and writes it to stdout.
2471 =head2 Rsync checksum caching
2473 An incremental backup with rsync compares attributes on the client
2474 with the last full backup. Any files with identical attributes
2475 are skipped. A full backup with rsync sets the --ignore-times
2476 option, which causes every file to be examined independent of
2479 Each file is examined by generating block checksums (default 2K
2480 blocks) on the receiving side (that's the BackupPC side), sending
2481 those checksums to the client, where the remote rsync matches those
2482 checksums with the corresponding file. The matching blocks and new
2483 data is sent back, allowing the client file to be reassembled.
2484 A checksum for the entire file is sent to as an extra check the
2485 the reconstructed file is correct.
2487 This results in significant disk IO and computation for BackupPC:
2488 every file in a full backup, or any file with non-matching attributes
2489 in an incremental backup, needs to be uncompressed, block checksums
2490 computed and sent. Then the receiving side reassembles the file and
2491 has to verify the whole-file checksum. Even if the file is identical,
2492 prior to 2.1.0, BackupPC had to read and uncompress the file twice,
2493 once to compute the block checksums and later to verify the whole-file
2496 Starting in 2.1.0, BackupPC supports optional checksum caching,
2497 which means the block and file checksums only need to be computed
2498 once for each file. This results in a significant performance
2499 improvement. This only works for compressed pool files.
2500 It is enabled by adding
2502 '--checksum-seed=32761',
2504 to $Conf{RsyncArgs} and $Conf{RsyncRestoreArgs}.
2506 Rsync versions prior to and including rsync-2.6.2 need a small patch to
2507 add support for the --checksum-seed option. This patch is available in
2508 the cygwin-rsyncd package at L<http://backuppc.sourceforge.net>.
2509 This patch is already included in rsync CVS, so it will be standard
2510 in future versions of rsync.
2512 When this option is present, BackupPC will add block and file checksums
2513 to the compressed pool file the next time a pool file is used and it
2514 doesn't already have cached checksums. The first time a new file is
2515 written to the pool, the checksums are not appended. The next time
2516 checksums are needed for a file, they are computed and added. So the
2517 full performance benefit of checksum caching won't be noticed until the
2518 third time a pool file is used (eg: the third full backup).
2520 With checksum caching enabled, there is a risk that should a file's contents
2521 in the pool be corrupted due to a disk problem, but the cached checksums
2522 are still correct, the corruption will not be detected by a full backup,
2523 since the file contents are no longer read and compared. To reduce the
2524 chance that this remains undetected, BackupPC can recheck cached checksums
2525 for a fraction of the files. This fraction is set with the
2526 $Conf{RsyncCsumCacheVerifyProb} setting. The default value of 0.01 means
2527 that 1% of the time a file's checksums are read, the checksums are verified.
2528 This reduces performance slightly, but, over time, ensures that files
2529 contents are in sync with the cached checksums.
2531 The format of the cached checksum data can be discovered by looking at
2532 the code. Basically, the first byte of the compressed file is changed
2533 to denote that checksums are appended. The block and file checksum
2534 data, plus some other information and magic word, are appended to the
2535 compressed file. This allows the cache update to be done in-place.
2537 =head2 File name mangling
2539 Backup file names are stored in "mangled" form. Each node of
2540 a path is preceded by "f" (mnemonic: file), and special characters
2541 (\n, \r, % and /) are URI-encoded as "%xx", where xx is the ascii
2542 character's hex value. So c:/craig/example.txt is now stored as
2543 fc/fcraig/fexample.txt.
2545 This was done mainly so meta-data could be stored alongside the backup
2546 files without name collisions. In particular, the attributes for the
2547 files in a directory are stored in a file called "attrib", and mangling
2548 avoids file name collisions (I discarded the idea of having a duplicate
2549 directory tree for every backup just to store the attributes). Other
2550 meta-data (eg: rsync checksums) could be stored in file names preceded
2551 by, eg, "c". There are two other benefits to mangling: the share name
2552 might contain "/" (eg: "/home/craig" for tar transport), and I wanted
2553 that represented as a single level in the storage tree. Secondly, as
2554 files are written to NewFileList for later processing by BackupPC_link,
2555 embedded newlines in the file's path will cause problems which are
2556 avoided by mangling.
2558 The CGI script undoes the mangling, so it is invisible to the user.
2559 Old (unmangled) backups are still supported by the CGI
2562 =head2 Special files
2564 Linux/unix file systems support several special file types: symbolic
2565 links, character and block device files, fifos (pipes) and unix-domain
2566 sockets. All except unix-domain sockets are supported by BackupPC
2567 (there's no point in backing up or restoring unix-domain sockets since
2568 they only have meaning after a process creates them). Symbolic links are
2569 stored as a plain file whose contents are the contents of the link (not
2570 the file it points to). This file is compressed and pooled like any
2571 normal file. Character and block device files are also stored as plain
2572 files, whose contents are two integers separated by a comma; the numbers
2573 are the major and minor device number. These files are compressed and
2574 pooled like any normal file. Fifo files are stored as empty plain files
2575 (which are not pooled since they have zero size). In all cases, the
2576 original file type is stored in the attrib file so it can be correctly
2579 Hardlinks are also supported. When GNU tar first encounters a file with
2580 more than one link (ie: hardlinks) it dumps it as a regular file. When
2581 it sees the second and subsequent hardlinks to the same file, it dumps
2582 just the hardlink information. BackupPC correctly recognizes these
2583 hardlinks and stores them just like symlinks: a regular text file
2584 whose contents is the path of the file linked to. The CGI script
2585 will download the original file when you click on a hardlink.
2587 Also, BackupPC_tarCreate has enough magic to re-create the hardlinks
2588 dynamically based on whether or not the original file and hardlinks
2589 are both included in the tar file. For example, imagine a/b/x is a
2590 hardlink to a/c/y. If you use BackupPC_tarCreate to restore directory
2591 a, then the tar file will include a/b/x as the original file and a/c/y
2592 will be a hardlink to a/b/x. If, instead you restore a/c, then the
2593 tar file will include a/c/y as the original file, not a hardlink.
2595 =head2 Attribute file format
2597 The unix attributes for the contents of a directory (all the files and
2598 directories in that directory) are stored in a file called attrib.
2599 There is a single attrib file for each directory in a backup.
2600 For example, if c:/craig contains a single file c:/craig/example.txt,
2601 that file would be stored as fc/fcraig/fexample.txt and there would be an
2602 attribute file in fc/fcraig/attrib (and also fc/attrib and ./attrib).
2603 The file fc/fcraig/attrib would contain a single entry containing the
2604 attributes for fc/fcraig/fexample.txt.
2606 The attrib file starts with a magic number, followed by the
2607 concatenation of the following information for each file:
2613 File name length in perl's pack "w" format (variable length base 128).
2621 The unix file type, mode, uid, gid and file size divided by 4GB and
2622 file size modulo 4GB (type mode uid gid sizeDiv4GB sizeMod4GB),
2623 in perl's pack "w" format (variable length base 128).
2627 The unix mtime (unix seconds) in perl's pack "N" format (32 bit integer).
2631 The attrib file is also compressed if compression is enabled.
2632 See the lib/BackupPC/Attrib.pm module for full details.
2634 Attribute files are pooled just like normal backup files. This saves
2635 space if all the files in a directory have the same attributes across
2636 multiple backups, which is common.
2638 =head2 Optimizations
2640 BackupPC doesn't care about the access time of files in the pool
2641 since it saves attribute meta-data separate from the files. Since
2642 BackupPC mostly does reads from disk, maintaining the access time of
2643 files generates a lot of unnecessary disk writes. So, provided
2644 BackupPC has a dedicated data disk, you should consider mounting
2645 BackupPC's data directory with the noatime attribute (see mount(1)).
2649 BackupPC isn't perfect (but it is getting better). Please see
2650 L<http://backuppc.sourceforge.net/faq/limitations.html> for a
2651 discussion of some of BackupPC's limitations.
2653 =head2 Security issues
2655 Please see L<http://backuppc.sourceforge.net/faq/security.html> for a
2656 discussion of some of various security issues.
2658 =head1 Configuration File
2660 The BackupPC configuration file resides in __CONFDIR__/config.pl.
2661 Optional per-PC configuration files reside in __CONFDIR__/pc/$host.pl
2662 (or __TOPDIR__/pc/$host/config.pl in non-FHS versions of BackupPC).
2663 This file can be used to override settings just for a particular PC.
2665 =head2 Modifying the main configuration file
2667 The configuration file is a perl script that is executed by BackupPC, so
2668 you should be careful to preserve the file syntax (punctuation, quotes
2669 etc) when you edit it. It is recommended that you use CVS, RCS or some
2670 other method of source control for changing config.pl.
2672 BackupPC reads or re-reads the main configuration file and
2673 the hosts file in three cases:
2683 When BackupPC is sent a HUP (-1) signal. Assuming you installed the
2684 init.d script, you can also do this with "/etc/init.d/backuppc reload".
2688 When the modification time of config.pl file changes. BackupPC
2689 checks the modification time once during each regular wakeup.
2693 Whenever you change the configuration file you can either do
2694 a kill -HUP BackupPC_pid or simply wait until the next regular
2697 Each time the configuration file is re-read a message is reported in the
2698 LOG file, so you can tail it (or view it via the CGI interface) to make
2699 sure your kill -HUP worked. Errors in parsing the configuration file are
2700 also reported in the LOG file.
2702 The optional per-PC configuration file (__CONFDIR__/pc/$host.pl or
2703 __TOPDIR__/pc/$host/config.pl in non-FHS versions of BackupPC)
2704 is read whenever it is needed by BackupPC_dump, BackupPC_link and others.
2706 =head1 Configuration Parameters
2708 The configuration parameters are divided into five general groups.
2709 The first group (general server configuration) provides general
2710 configuration for BackupPC. The next two groups describe what to
2711 backup, when to do it, and how long to keep it. The fourth group
2712 are settings for email reminders, and the final group contains
2713 settings for the CGI interface.
2715 All configuration settings in the second through fifth groups can
2716 be overridden by the per-PC config.pl file.
2720 =head1 Version Numbers
2722 Starting with v1.4.0 BackupPC uses a X.Y.Z version numbering system,
2723 instead of X.0Y. The first digit is for major new releases, the middle
2724 digit is for significant feature releases and improvements (most of
2725 the releases have been in this category), and the last digit is for
2726 bug fixes. You should think of the old 1.00, 1.01, 1.02 and 1.03 as
2727 1..0, 1.1.0, 1.2.0 and 1.3.0.
2729 Additionally, patches might be made available. A patched version
2730 number is of the form X.Y.ZplN (eg: 2.1.0pl2), where N is the
2735 Craig Barratt <cbarratt@users.sourceforge.net>
2737 See L<http://backuppc.sourceforge.net>.
2741 Copyright (C) 2001-2006 Craig Barratt
2745 Ryan Kucera contributed the directory navigation code and images
2746 for v1.5.0. He contributed the first skeleton of BackupPC_restore.
2747 He also added a significant revision to the CGI interface, including
2748 CSS tags, in v2.1.0, and designed the BackupPC logo.
2750 Xavier Nicollet, with additions from Guillaume Filion, added the
2751 internationalization (i18n) support to the CGI interface for v2.0.0.
2752 Xavier provided the French translation fr.pm, with additions from
2755 Guillaume Filion wrote BackupPC_zipCreate and added the CGI support
2756 for zip download, in addition to some CGI cleanup, for v1.5.0.
2757 Guillaume continues to support fr.pm updates for each new version.
2759 Josh Marshall implemented the Archive feature in v2.1.0.
2761 Ludovic Drolez supports the BackupPC Debian package.
2763 Javier Gonzalez provided the Spanish translation, es.pm for v2.0.0.
2765 Manfred Herrmann provided the German translation, de.pm for v2.0.0.
2766 Manfred continues to support de.pm updates for each new version,
2767 together with some help frmo Ralph Paßgang.
2769 Lorenzo Cappelletti provided the Italian translation, it.pm for v2.1.0.
2771 Lieven Bridts provided the Dutch translation, nl.pm, for v2.1.0,
2772 with some tweaks from Guus Houtzager.
2774 Reginaldo Ferreira provided the Portuguese Brazillian translation
2775 pt_br.pm for v2.2.0.
2777 Rich Duzenbury provided the RSS feed option to the CGI interface.
2779 Many people have reported bugs, made useful suggestions and helped
2780 with testing; see the ChangeLog and the mail lists.
2782 Your name could appear here in the next version!
2786 This program is free software; you can redistribute it and/or modify it
2787 under the terms of the GNU General Public License as published by the
2788 Free Software Foundation; either version 2 of the License, or (at your
2789 option) any later version.
2791 This program is distributed in the hope that it will be useful,
2792 but WITHOUT ANY WARRANTY; without even the implied warranty of
2793 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
2794 General Public License for more details.
2796 You should have received a copy of the GNU General Public License in the
2797 LICENSE file along with this program; if not, write to the Free Software
2798 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.