HP A3716A DDS-3 Autoloader User's Manual - 3716-96001

Choosing a Backup Strategy
Choice of Backup Strategy
5-2
Choice of Backup Strategy
Note It is highly recommended that you use the autoloader as described here, that
is, one tape per day and one cleaning cartridge in a magazine. Using more
tapes per day will cause lower reliability and reduce the autoloaders useful
life.
How you organize backup depends very much on how frequently your data
changes, how extensive the changes are and how valuable you consider the
information. What is essential is that you follow a routine, so that backup is
regular and trouble-free.
There are many systematic methods for backing up data on a regular basis. The
methods recommended in this section are very simple to implement; they also
maintain several historical copies of the data so that even if one copy is lost, you
have a high probability of recovering your lost data.
To ensure longevity of your tape cartridges, it is important to follow the tape
maintenance recommendations outlined in Chapter 6 of this guide. If you follow
the backup method described in this section, you should renew your tapes each
year. This allows for a cartridge to be inserted at most about 100 times, allowing
for a number of restores in addition to the backups. This is well within the
guidelines detailed on page 6-6.
Build a cleaning cycle into your backup regime to ensure that it is not forgotten.
The table on page 6-2 gives the recommended frequency.
Method 1: One Magazine Per Week
If your system disks are of a size that can be fully backed up onto a single tape
cartridge, the easiest method of organizing backup is to perform a full backup
each night. One magazine will then hold a weeks backup together with a
cleaning cartridge.
Store the magazines offsite or in a fireproof safe for as long as you want to
preserve the data. For example, if you want to be able to restore data from up
to eight weeks ago (a backup horizon of eight weeks), you will need nine
magazines. Reuse the earliest magazine for the current weeks backup.
This straightforward pattern can be modified to suit particular circumstances:
n Extend the backup horizon by using more magazines.
n For larger system disks, consider a combination of a full backup spanning
several tapes on Friday and differential or incremental backups on the other
days. A differential backup only backs up new or modified files since the