Backup Routines; Model 1: Daily Backup; Model 2: Weekly Rotation With Daily Backup - HP A3542A User Manual

Backup routines

Your backup routine depends on how frequently the data changes, how extensive the changes are, and how
valuable the data is. It is essential that you follow a routine, so data backup is regular and trouble-free. The
following three models present routines which are commonly used. In each model, a "'set"' of cartridges is
the smallest number of tapes that will hold a full or partial backup.
Keep a record of the number times each set is used, so a set can be replaced when its recommended write
life (100 insertions) is reached. The replaced set can still be kept for read-only use, but should not be used
for writing.

Model 1: Daily backup

This is the simplest backup model. All of the data is backed up onto a single set of tapes at the end of each
work day. If data is lost, it is simply restored from the previous day's backup. It is the least secure model of
backup, because if the cartridge is lost, destroyed or damaged, the data is lost forever.
Number of cartridges needed:

Model 2: Weekly rotation with daily backup

In this model, you perform a full backup every Friday, and a partial backup on Monday, Tuesday,
Wednesday, and Thursday. Partial backups are made only on those files which have changed since the
previous backup.
Two sets of tapes, A and B, are used in rotation for the weekly full backups. On the first Friday, you make a
full image copy of your disks on tape set A. On the second Friday, use set B for a full backup. On the third
Friday, use set A again. This way, there are always two generations of full backup in existence. Store the sets
off-site, preferably in a fire-proof safe, so if there is a fire or equipment is stolen from site, the backup is
unaffected.
Four sets of tapes are used for the daily backups, one set for each day. Because only changed files are saved,
these backups are very quick.
Number of cartridges needed:
2-8
1 set for full backup
2 sets for full backup
4 sets for partial backup
A3542A DDS-3 Tape Drive User's Guide