Backing up filesystems

About backups

A ``backup'' is a copy on external storage media (floppy disks or tape), of files on your hard disk. A ``filesystem backup'' is a copy of the files in the root filesystem or another regularly mounted filesystem (such as /u). See ``Administering filesystems'' for more information about filesystems.

Files and filesystems can be damaged and data can be lost through:

power surges and interruptions (make certain you have a surge protector).
hardware failures (particularly the hard disk).
user errors (accidental removal of important files).

You should back up your filesystems regularly so you have up-to-date copies from which to restore lost data. Use the Backup Manager to back up and restore filesystems.

NOTE: You must be logged in as root or have backup authorizations to create backups with the Backup Manager. If the filesystem is unmounted prior to running a backup, you must be logged in as root or also have sysadmin authorizations to mount the filesystem. See ``Assigning subsystem authorizations''.

A ``scheduled backup'' is a regular backup performed according to a predefined schedule. The backup schedule determines the days of the week to perform the backup, which backup level to perform on which days, and so forth. When you use a backup schedule, you do not need to save the entire filesystem each time you perform a backup. Instead, you can perform an ``incremental backup'', which saves only those files that have changed since a specified time. See ``Understanding incremental backups''.

If your system has many users and a large number of files that are modified daily, you should create a backup schedule and perform regularly scheduled backups. To schedule a local filesystem to be backed up regularly, see ``Adding, modifying, and removing filesystem backup schedules''. To schedule backups for a remote filesystem, see ``Adding remote filesystems to the backup schedule''.

NOTE: To back up remote filesystems with the Backup Manager, you must first establish backup user equivalence.

An ``unscheduled backup'' is a complete, informal backup of a filesystem or directory. Unscheduled backups copy the entire filesystem or directory, not just the modified files, and thus might require many storage media volumes. If your backup requirements are simple, you might be able to perform unscheduled backups on a regular basis. (we recommend at least once a week).