TMF Planning and Configuration Guide (H06.05+)

Configuring TMF for Backup and Recovery
HP NonStop TMF Planning and Configuration Guide—540136-002
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Online Dump File Generations
Online Dump File Generations
The TMF catalog can keep the dump entries for several generations of each database
table or file that you dump. The number of generations depends upon the value of the
RETAINDEPTH parameter specified in the ALTER CATALOG command. By default,
the TMF catalog maintains three generations of each file dumped in online dumps.
When an online dump expires, its dump entries are deleted from the catalog. Audit
dumps required only by the expired online dump automatically expire at the same time.
Which Files to Dump
Tables or files without a valid online dump cannot be recovered by the file recovery
process. Therefore, all of the tables and files in production databases used by your
applications should be protected regularly by online dumps. Your system might
include some tables and files that are protected by TMF but which are not critical to
your day-to-day business operation; use your judgment whether you need to dump
those files.
You should make your online dumps on a volume-by-volume basis. Nonmirrored
volumes should be dumped more frequently because they do not have mirrored fault
tolerance to protect them.
If you have multiple tape drives, you can dump multiple disk volumes or sets of files
simultaneously. You can dump some groups on one day, and others the next.
How Often to Dump
How often to make online dumps depends upon how quickly you need to recover your
database tables and files after a media loss. When you increase the frequency of your
online dumps:
•
The file recovery process performs faster because fewer audit records need to be
applied.
•
The number of audit dumps retained in the catalog is reduced.
•
Dumping to tape uses fewer tape reels for the retained audit dumps.
•
More operator interaction is required.
TMF does not require you to make online dumps at particular times; you can make
online dumps any time, as long as TMF is started. You should, however, establish a
regular schedule for making online dumps.
You should make online dumps of key files frequently. Files that are used less often or
that are more static in nature can be dumped less frequently. Files that are dumped
more often can be recovered faster than files that are dumped less often.
As a general rule, you should make online dumps of all your production database
tables and files at least once a week. If you follow this rule, the file recovery process