Red Hat Linux 7 Unleashed

Red Hat Linux 7 Unleashed

By William Ball

Selecting a Backup Tool

Many tools are available for making backups. In addition to numerous third-party applications, Red Hat Linux comes with some standard tools for performing this task. This section examines two of them, tar and cpio.

tar and cpio are very similar. Both are capable of storing and retrieving data from almost any media. In addition, both tar and cpio are ideal for small systems, which Red Hat Linux systems often are. For example, the following tar command saves all files under /home to the standard output (which can then be redirected to your system's backup device or directory):


   $ tar c /home >home.tar

The c option tells tar to create a new archive, and the specified directory is used to gather the files. The output is redirected to the file named home.tar.

cpio, although similar to the tar command, has several advantages. First, it packs data more efficiently. Second, it is designed to back up arbitrary sets of files. (tar is designed to back up subdirectories.) Third, cpio is designed to handle backups that span over several tapes. Finally, cpio skips over bad sections on a tape and continues, but tar crashes and burns.

NOTE

The GNU version of tar included with Red Hat Linux has several options useful for multi-volume backup operations. To perform a multivolume backup or restore, use tar's M option on the command line. For example, to create a compressed backup of the /home directory via multiple floppy disks, use tar –cvMf /dev/fd0 /home.

AMANDA

If you're looking for more sophisticated backup software, you can also try AMANDA, the Advanced Maryland Automatic Network Disk Archiver. This free software, from the University of Maryland at College Park, can be used over a network to back up multiple computer filesystems to a single, large-capacity tape drive. Some features include graceful error recovery, compression, scheduling, encryption, and high-speed backup operation.

Red Hat Linux does not include a copy of AMANDA, which is meant for use with high-capacity tape drives, but which may also be used with floptical, CDR, or CD -RW drives. AMANDA is a sophisticated backup tool with features rivaling those of commercial software backup products. Some of these features include network operation, incremental backups, scheduling, and full dump and restore operations.

You can retrieve a copy of AMANDA from ftp://ftp.amanda.org/pub/amanda. The file as distributed by amanda.org will be in a compressed tar archive. Decompress the file and follow instructions for installation. If you'd prefer, you can download a copy in RPM format from http://rpmfind.net/linux/RPM/amanda.html.

To use AMANDA, you'll first need to assign correct user and group permissions to a designated holding directory, then create and edit a default configuration file. The configuration file tells AMANDA how much disk space to use, and what type of backup device is available. After initial configuration, AMANDA commands (and options) are generally run using the su command like this:


   # su amanda -c 
   
      "amandacommand [cmdoptions]"

AMANDA is a complex but capable backup system (begging for a graphical interface!). For a short tutorial by John R. Jackson, browse to http://www.backupcentral.com/amanda.html. You'll find an FAQ, along with other documentation, and example configuration files under the /usr/share/doc/amanda-2.4.1p1/ directory. AMANDA Tape Backup information, along with the latest release may be found at http://sourceforge.net/project/?group_id=120. For more information, see http://www.amanda.org.

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