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

Choosing a Backup Strategy
Choice of Backup Strategy
5-3
last full backup. An incremental backup backs up new or modified files
since the last full or incremental backup. Differential backups make locating
a file to be restored easier but take up more space than incremental backups.
n Consider archiving a magazine at intervals (perhaps quarterly) if there is a
possibility you will need to retrieve historical data in future.
Method 2: Magazine Rotation
If you want to minimize the number of magazines held in storage, magazines
can be arranged in cycles of different frequency, such as weekly magazines and
monthly magazines.
For example, you can preserve data from up to eight weeks ago using six
magazines:
n Label three of the magazines: Week 1, Week 2, Week 3.
n Label the other three: Month 1, Month 2, Month 3. (A month is considered to
be four weeks for this example.)
Each month, use the weekly magazines for the first three weeks. For the fourth
week, use one of the monthly magazines in rotation.
You can extend this backup routine in several ways:
n Use more monthly magazines. Thirteen monthly magazines would give a
backup horizon of a whole year.
n Build in another more infrequent cycle. For example, you could have a set of
quarterly magazines used for a full backup on the last working day of each
quarter. These could then be archived indefinitely.
Figure 5.1 Six-magazine rotation