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Explore Backup Tools in UNIX

The UNIX system gives a powerful set of robust backup tools and for the most part the same set of tools is available for most of the UNIX versions currently available on the market today. Some of the most common tools are listed in Table 1. The major benefits for common availability of the tools are consistency and compatibility. For instance, the basic operation of the commands is the same so that if the administrator develops custom scripts, those scripts can be used across a variety of UNIX systems with major operating system changes. Second, if the backed up data is compatible with different UNIX versions, backups can be made on one system and restored on another. This sort of thing isn’t something that would be done every day, but administrators may like the option of doing so.

Table 1: Dump Command-Line Options

Tool and Description

dump: Performs full and incremental backups of file systems (Solaris, ufsdump—for Linux and HP-UX, the command is known as
dump).
dd: Can be used to perform image-type backups.
restore: Used to retrieve file and directories from backups taken with the dump command (Solaris uses ufsrestore; 
restore for the other operating systems).
tar: General-purpose archiving tool.
volcopy: Performs full image backup of a file system for the Solaris platform.
0-9: The backup dump level to use; this controls which files will be saved.
-D: Save the backup to a diskette device. This is
somewhat limited since diskettes are quite small and can’t store much information.
-S: Determine the total size of a backup, without actually
doing the backup.
-a: Specify the archive file to use so that when a restore
is performed, it can be searched to determine if a particular file/directory is
contained within the backup.
-b: Use the blocking factor when making the backup.
The default is 20 and is specific to the storage media used.
-f: Specifies the dump file, which is usually a storage
device such as tape or disk. When the “-“ character is used, the standard output
should be used instead.
-l: Control the backup storage media so that when the
dump is complete, dump will pause to give the storage device time to
automatically reload a new tape or media.
-n: Inform the operator when dump requests attention,
such as mounting a new tape.
-t: Controls the amount of time to wait for the storage
device to autoload another tape. Used with the –l option.
-v: Perform a verification on the backup media as the
last step in the process.
-w: Issue a warning when dump detects a file system
that hasn’t been backed up.

To perform a full backup of the / file system to a local tape unit, use the following command:

ufsdump 0f /dev/st0 /