8.4.2. Backup Technologies

Red Hat Enterprise Linux comes with several different programs for backing up and restoring data. By themselves, these utility programs do not constitute a complete backup solution. However, they can be used as the nucleus of such a solution.

Note

As noted in Section 8.2.6.1, “Restoring From Bare Metal”, most computers based on the standard PC architecture do not possess the necessary functionality to boot directly from a backup tape. Consequently, Red Hat Enterprise Linux is not capable of performing a tape boot when running on such hardware.
However, it is also possible to use your Red Hat Enterprise Linux CD-ROM as a system recovery environment; for more information see the chapter on basic system recovery in the System Administrators Guide.

8.4.2.1. tar

The tar utility is well known among UNIX system administrators. It is the archiving method of choice for sharing ad-hoc bits of source code and files between systems. The tar implementation included with Red Hat Enterprise Linux is GNU tar, one of the more feature-rich tar implementations.
Using tar, backing up the contents of a directory can be as simple as issuing a command similar to the following:
 tar cf /mnt/backup/home-backup.tar /home/ 
This command creates an archive file called home-backup.tar in /mnt/backup/. The archive contains the contents of the /home/ directory.
The resulting archive file will be nearly as large as the data being backed up. Depending on the type of data being backed up, compressing the archive file can result in significant size reductions. The archive file can be compressed by adding a single option to the previous command:
 tar czf /mnt/backup/home-backup.tar.gz /home/ 
The resulting home-backup.tar.gz archive file is now gzip compressed[30].
There are many other options to tar; to learn more about them, read the tar(1) man page.


[30] The .gz extension is traditionally used to signify that the file has been compressed with gzip. Sometimes .tar.gz is shortened to .tgz to keep file names reasonably sized.