Saving Data With dump

Saving Data With dump

This section describes how to perform backups with the dump utility.

Saving a Filesystem With dump

The dump utility archives not only regular files, but also device files and special files such as links and named pipes. To recover files from an archive, you use the restore command.The date on which you last ran the dump program is stored in the file /etc/dumpdates when you specify the u option to indicate an update.

This command backs up all files on the /usr filesystem:

dump 0 /dev/usr

Note: The 0 in the example specifies the increment level. Refer to the next section for an explanation of level numbers.

Incremental Backups With dump

The dump utility is designed for incremental backups, and it archives not only regular files and directories, but also special files, links, and pipes.

To create an incremental backup, specify an increment number when you use dump. The dump program archives all files that have changed since the last appropriate increment and special files such as links and named pipes. To recover files from an archive, use the restore command.

The dump program is designed specifically to create incremental backups. It refers to the increments as levels, and each level is assigned a number:

A level 0 backup archives all files in a filesystem.
Backup levels 1-9 archive all files that have changed since the previous backup of the same or lesser level.

For example, this command backs up all files on the /usr filesystem:

dump 0 /dev/usr

This command backs up those files that have changed since the previous level 0 dump:

dump 1 /dev/usr

This command archives those files that have changed since the previous level 1 dump:

dump 2 /dev/usr

If the next dump command you give specifies level 1, dump backs up the files that have changed since the last level 0, but not those that have changed since the last level 2.

This numbering system gives you enormous flexibility so you can create a backup schedule to fit your specific needs.