Special:Badtitle/NS100:Which backup program for filesystems is better?

Both dump and gnutar have advantages as well as disadvantages.

Dump can backup filesystems that are unmounted. Dump does not change filesystem metadata when the filesystems are backed up. Using dump, the backup window is reduced. Generally, dumping filesystem is faster than any other backup method. The main disadvantage of dump is the backed up filesystem data might be corrupted. Dump does not provide filesystem consistent view. Dumping an active filesystem may result in a backup image that cannot be restored. Dump is also very filesystem specific: a dump from one OS cannot be restored on a different OS. For more information, see dump information. Dump supports backup of only complete filesystems. Finer granularity of filesystem backups is not possible.

GNUTAR allows backup of directories and has the ability to exclude some directories and files using regular expressions. The GNUTAR archive is also portable between different OSes. GNUTAR can be used to backup live filesystems. Active files are included in the backup and you get a warning if a file is changed while being read; it's up to you to decide if that is bad or not for a particular file. GNUTAR normally modifies the last access time of the files (using option --atime-preserve modifies the ctime, which is even worse!). Older versions (before 1.15) of GNUTAR do not back up ACLs or extended filesystem attributes. Note: the version number of importance here is the one on the clients.

To avoid trouble with active filesystems, or modifying metadata like atime, an alternative is to use hardware snapshots or LVM snapshots. Use snapshot to create a copy of the filesystem and backup the copy using GNUTAR or DUMP program.

For MacOS X, tar should be used instead of dump. The dump program does not back up extended attributes such as resource forks built in to the HFS+ filesystems while, as of MacOS 10.4 and later, tar supports this and other extended attributes. Apple's developer note provides more information concerning native MacOS tools and their advantages/disadvantages.