Frequency and retention of backup copies

Generally, the more frequently you copy, the less time recovery takes. The further back in time your old copies go, the further back in time you can recover. (Remember that program logic errors are sometimes not discovered for weeks.) Conversely, making each new copy requires work, and each old copy that you save uses additional resources.

Consider the following questions when making backup copies of databases:

• How frequently should I make new copies?
• How long should I keep old (back-level) copies?

There are no precise answers to these questions.

The only firm guidelines are these:

• If a database is composed of several data sets, be sure to copy all of the data sets at the same time.
• If you reorganize a database, immediately make a new backup copy of it. (This is not necessary for online DEDBs or HISAM reorganizations.)
• If you create a new database, immediately make a backup copy of it.
• If you perform a time-stamp recovery, make a backup copy for use in subsequent recoveries.