-modification time) since the last successful full backup. To be safe,
-BackupPC backups all files that have changed since one hour prior to the
-start of the last successful full backup. BackupPC can also be configured
-to keep a certain number of incremental backups, and to keep a smaller
-number of very old incremental backups. (BackupPC does not support
-multi-level incremental backups, although it would be easy to do so.)
+modification time) since the last successful full backup. For SMB and
+tar, BackupPC backups all files that have changed since one hour prior to the
+start of the last successful full backup. Rsync is more clever: any files
+who attributes have changed (ie: uid, gid, mtime, modes, size) since the
+last full are backed up. Deleted and new files are also detected by
+Rsync incrementals (SMB and tar are not able to detect deleted files or
+new files whose modification time is prior to the last full dump.
+
+BackupPC can also be configured to keep a certain number of incremental
+backups, and to keep a smaller number of very old incremental backups.
+(BackupPC does not support multi-level incremental backups, although it
+would be easy to do so.)