| 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. |