Reference Topics
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Guidelines for Setting Retention Periods
The length of time that you must retain data usually depends on how likely
you are to need it after a certain period of time. Some data, such as tax and
other financial records, have legal requirements for retention. Other data, such
as preliminary documents can probably be expired when the final version is
complete.
How long you keep a backup also depends on what you need to recover from
it. For example, if day-to-day changes are critical, you must keep all the
incrementals in addition to full backups for as long as you need the data. If
incrementals only track work in progress toward monthly reports, then you
can probably expire the incrementals sooner and rely on the full backups for
long-term recovery.
When deciding on retention periods, establish guidelines that apply to most of
your data. After establishing guidelines, note files or directories that have
retention requirements outside of these guidelines and plan to create a separate
class (or classes) for them. For example, placing files and directories with
longer retention requirements in a separate class allows you to schedule longer
retention times for them without keeping all the others for the longer time
period.
Another consideration for data retention is off-site storage of the backup
media. This protects against fires or other disasters that occur at the primary
site. Set the retention period to infinite for backups you must retain for more
than one year.
• One method of implementing off-site disaster recovery is to use the
duplicate feature to make a second copy for offsite storage.
• Another approach is to send monthly or weekly automatic full backups to
an off-site storage facility. To restore the data, you get the media from off-
site storage (a total directory or disk restore with incrementals requires the
last full backup plus all incrementals).
• You can also configure an extra set of schedules for the backups to create
duplicates for off-site storage.
Regardless of the method you use for off-site storage, ensure that you
configure adequate retention periods. You can use the NetBackup import
feature to retrieve expired backups but it is easiest just to set an adequate
retention period.
NetBackup 3.2 System Administrator's Guide for Windows NT
NetBackup 3.2 System Administrator's Guide for Windows NT
