Summary
Now that you have completed this chapter, you should have a firm understanding of the following:

Backing up data is one of the most important functions a network administrator can perform. Data can become lost or corrupted for a variety of reasons. The most important thing is to have good backups available to restore the lost data quickly and accurately.

There are three basic backup strategies: Full, Incremental, and Differential. Full backups take the longest but are the easiest to restore. Incremental backups take less time but are harder to restore since there are more tapes involved. Differential backups are a compromise, taking less time than a full backup while being easier to restore than incremental.

Magnetic tape has traditionally been the primary backup media due to its high capacity and relatively low cost. Recently some newer technologies such as removable drives, Jaz™ disks and writable CDs have begun to replace tape drives for backing up quantities of data of less than 1 Gigabyte.

The UNIX operating system has several command line backup utilities available, which include tar (tape archive) , jar (java archive) and compress / uncompress. The tar command combines multiple files into an archive file but does not compress them. The tar command can be used to archive and extract files. The compress command is used to reduce the disk space taken up by a file. The uncompress command expands files back to their original size so that you can work with the file. The jar utility combines the capabilities of the tar command with the compress utility and can simultaneously archive and compress files. When they are extracted they are automatically uncompressed.

CDE has some graphical tools to archive and compress files which are available from the Files subpanel on the front panel. CDE File Manager can be used to extract and uncompress files.