Chapter 11. Backing up an XFS file system

• Perform backups to regular file images.

  Only one backup can be written to a regular file.

• Perform backups to tape drives.

  You can also write multiple backups to the same tape by using the xfsdump utility. A backup can span multiple tapes.

  To back up multiple file systems to a single tape device, write the backup to a tape that already contains an XFS backup. This appends the new backup to the previous one. By default, xfsdump never overwrites existing backups.

• Create incremental backups.

  The xfsdump utility uses dump levels to determine a base backup to which other backups are relative. Numbers from 0 to 9 refer to increasing dump levels. An incremental backup only backs up files that have changed since the last dump of a lower level:

  • To perform a full backup, perform a level 0 dump on the file system.
  • A level 1 dump is the first incremental backup after a full backup. The next incremental backup would be level 2, which only backs up files that have changed since the last level 1 dump; and so on, to a maximum of level 9.
• Exclude files from a backup by using size, subtree, or inode flags to filter them.

Prerequisites

• An XFS file system that you can back up.
• Another file system or a tape drive where you can store the backup.

Procedure

• Use the following command to back up an XFS file system:

  # xfsdump -l level [-L label] \ -f backup-destination path-to-xfs-filesystem

  • Replace level with the dump level of your backup. Use 0 to perform a full backup or 1 to 9 to perform consequent incremental backups.
  • Replace backup-destination with the path where you want to store your backup. The destination can be a regular file, a tape drive, or a remote tape device. For example, /backup-files/Data.xfsdump for a file or /dev/st0 for a tape drive.
  • Replace path-to-xfs-filesystem with the mount point of the XFS file system you want to back up. For example, /mnt/data/. The file system must be mounted.

  • When backing up multiple file systems and saving them on a single tape device, add a session label to each backup by using -L label. This makes backups easier to identify when restoring. Replace label with any name for your backup: for example, backup_data.

    For example, to back up the content of XFS file systems mounted on the /boot/ and /data/ directories as files in /backup-files/:

    # xfsdump -l 0 -f /backup-files/boot.xfsdump /boot

    # xfsdump -l 0 -f /backup-files/data.xfsdump /data

• To back up multiple file systems on a single tape device, add a session label by using the -L label option:

  # xfsdump -l 0 -L "backup_boot" -f /dev/st0 /boot

  # xfsdump -l 0 -L "backup_data" -f /dev/st0 /data

  For more information, see the xfsdump(8) man page on your system.