5 XFS is a high performance journaling filesystem which originated
6 on the SGI IRIX platform. It is completely multi-threaded, can
7 support large files and large filesystems, extended attributes,
8 variable block sizes, is extent based, and makes extensive use of
9 Btrees (directories, extents, free space) to aid both performance
12 Refer to the documentation at http://oss.sgi.com/projects/xfs/
13 for further details. This implementation is on-disk compatible
14 with the IRIX version of XFS.
20 When mounting an XFS filesystem, the following options are accepted.
23 Sets the preferred buffered I/O size (default size is 64K).
24 "size" must be expressed as the logarithm (base2) of the
26 Valid values for this option are 14 through 16, inclusive
27 (i.e. 16K, 32K, and 64K bytes). On machines with a 4K
28 pagesize, 13 (8K bytes) is also a valid size.
29 The preferred buffered I/O size can also be altered on an
30 individual file basis using the ioctl(2) system call.
33 When inode clusters are emptied of inodes, keep them around
34 on the disk (ikeep) - this is the traditional XFS behaviour
35 and is still the default for now. Using the noikeep option,
36 inode clusters are returned to the free space pool.
39 Set the number of in-memory log buffers. Valid numbers range
41 The default value is 8 buffers for filesystems with a
42 blocksize of 64K, 4 buffers for filesystems with a blocksize
43 of 32K, 3 buffers for filesystems with a blocksize of 16K
44 and 2 buffers for all other configurations. Increasing the
45 number of buffers may increase performance on some workloads
46 at the cost of the memory used for the additional log buffers
47 and their associated control structures.
50 Set the size of each in-memory log buffer.
51 Size may be specified in bytes, or in kilobytes with a "k" suffix.
52 Valid sizes for version 1 and version 2 logs are 16384 (16k) and
53 32768 (32k). Valid sizes for version 2 logs also include
54 65536 (64k), 131072 (128k) and 262144 (256k).
55 The default value for machines with more than 32MB of memory
56 is 32768, machines with less memory use 16384 by default.
58 logdev=device and rtdev=device
59 Use an external log (metadata journal) and/or real-time device.
60 An XFS filesystem has up to three parts: a data section, a log
61 section, and a real-time section. The real-time section is
62 optional, and the log section can be separate from the data
63 section or contained within it.
66 Data allocations will not be aligned at stripe unit boundaries.
69 Access timestamps are not updated when a file is read.
72 The filesystem will be mounted without running log recovery.
73 If the filesystem was not cleanly unmounted, it is likely to
74 be inconsistent when mounted in "norecovery" mode.
75 Some files or directories may not be accessible because of this.
76 Filesystems mounted "norecovery" must be mounted read-only or
80 Don't check for double mounted file systems using the file system uuid.
81 This is useful to mount LVM snapshot volumes.
84 Make O_SYNC writes implement true O_SYNC. WITHOUT this option,
85 Linux XFS behaves as if an "osyncisdsync" option is used,
86 which will make writes to files opened with the O_SYNC flag set
87 behave as if the O_DSYNC flag had been used instead.
88 This can result in better performance without compromising
90 However if this option is not in effect, timestamp updates from
91 O_SYNC writes can be lost if the system crashes.
92 If timestamp updates are critical, use the osyncisosync option.
94 quota/usrquota/uqnoenforce
95 User disk quota accounting enabled, and limits (optionally)
99 Group disk quota accounting enabled and limits (optionally)
102 sunit=value and swidth=value
103 Used to specify the stripe unit and width for a RAID device or
104 a stripe volume. "value" must be specified in 512-byte block
106 If this option is not specified and the filesystem was made on
107 a stripe volume or the stripe width or unit were specified for
108 the RAID device at mkfs time, then the mount system call will
109 restore the value from the superblock. For filesystems that
110 are made directly on RAID devices, these options can be used
111 to override the information in the superblock if the underlying
112 disk layout changes after the filesystem has been created.
113 The "swidth" option is required if the "sunit" option has been
114 specified, and must be a multiple of the "sunit" value.
119 The following sysctls are available for the XFS filesystem:
121 fs.xfs.stats_clear (Min: 0 Default: 0 Max: 1)
122 Setting this to "1" clears accumulated XFS statistics
123 in /proc/fs/xfs/stat. It then immediately reset to "0".
125 fs.xfs.sync_interval (Min: HZ Default: 30*HZ Max: 60*HZ)
126 The interval at which the xfssyncd thread for xfs filesystems
127 flushes metadata out to disk. This thread will flush log
128 activity out, and do some processing on unlinked inodes
130 fs.xfs.error_level (Min: 0 Default: 3 Max: 11)
131 A volume knob for error reporting when internal errors occur.
132 This will generate detailed messages & backtraces for filesystem
133 shutdowns, for example. Current threshold values are:
139 fs.xfs.panic_mask (Min: 0 Default: 0 Max: 127)
140 Causes certain error conditions to call BUG(). Value is a bitmask;
141 AND together the tags which represent errors which should cause panics:
144 XFS_PTAG_IFLUSH 0x00000001
145 XFS_PTAG_LOGRES 0x00000002
146 XFS_PTAG_AILDELETE 0x00000004
147 XFS_PTAG_ERROR_REPORT 0x00000008
148 XFS_PTAG_SHUTDOWN_CORRUPT 0x00000010
149 XFS_PTAG_SHUTDOWN_IOERROR 0x00000020
150 XFS_PTAG_SHUTDOWN_LOGERROR 0x00000040
152 This option is intended for debugging only.
154 fs.xfs.irix_symlink_mode (Min: 0 Default: 0 Max: 1)
155 Controls whether symlinks are created with mode 0777 (default)
156 or whether their mode is affected by the umask (irix mode).
158 fs.xfs.irix_sgid_inherit (Min: 0 Default: 0 Max: 1)
159 Controls files created in SGID directories.
160 If the group ID of the new file does not match the effective group
161 ID or one of the supplementary group IDs of the parent dir, the
162 ISGID bit is cleared if the irix_sgid_inherit compatibility sysctl
165 fs.xfs.restrict_chown (Min: 0 Default: 1 Max: 1)
166 Controls whether unprivileged users can use chown to "give away"
167 a file to another user.
169 fs.xfs.inherit_sync (Min: 0 Default: 1 Max 1)
170 Setting this to "1" will cause the "sync" flag set
171 by the chattr(1) command on a directory to be
172 inherited by files in that directory.
174 fs.xfs.inherit_nodump (Min: 0 Default: 1 Max 1)
175 Setting this to "1" will cause the "nodump" flag set
176 by the chattr(1) command on a directory to be
177 inherited by files in that directory.
179 fs.xfs.inherit_noatime (Min: 0 Default: 1 Max 1)
180 Setting this to "1" will cause the "noatime" flag set
181 by the chattr(1) command on a directory to be
182 inherited by files in that directory.
184 vm.pagebuf.stats_clear (Min: 0 Default: 0 Max: 1)
185 Setting this to "1" clears accumulated pagebuf statistics
186 in /proc/fs/pagebuf/stat. It then immediately reset to "0".
188 vm.pagebuf.flush_age (Min: 1*HZ Default: 15*HZ Max: 300*HZ)
189 The age at which dirty metadata buffers are flushed to disk
191 vm.pagebuf.flush_int (Min: HZ/2 Default: HZ Max: 30*HZ)
192 The interval at which the list of dirty metadata buffers is