TMF Introduction (G06.26+)

Transaction Protection and Database Recovery
HP NonStop TMF Introduction—522414-002
3-5
Audit Volumes
Audit Volumes
Audit volumes are the disk volumes that contain audit-trail files. There are three types
of audit volumes: active-audit volumes, overflow-audit volumes, and restore-audit
volumes.
Active-Audit Volume
The disk volumes that contain active-audit-trail files are called active-audit volumes.
HP requires that you place audit-trail files and audited database files on separate disk
volumes so that the database files and audit-trail files cannot be damaged by the same
failure.
Overflow-Audit Volume
The system manager can configure overflow-audit volumes to be used when the active
audit trail is nearing full capacity and no files are available for a rollover. The oldest
audit-trail files are copied to the overflow volumes: this allows audit-trail files to be
reused.
Typically, overflow volumes are used if TMF is temporarily generating audit records at
a higher rate than anticipated when the audit trail was configured, or if secondary
storage media is not available for audit dumps.
Restore-Audit Volume
Restore-audit volumes contain audit-trail files restored from an audit dump as part of a
TMF recovery procedure. If you configure automatic audit dumping, you must
configure restore-audit volumes. Restore-audit volumes are used during file recovery.
During recovery of database files, TMF applies changes from audit-trail files to the
database. If TMF requires an audit-trail file that is no longer available on the system,
but is archived on tape, TMF restores that file from an audit dump on the tape to a
restore-audit volume on disk. TMF then reads the audit-trail file and applies changes
to the database. When the recovery process completes, TMF purges this file and all
other unneeded files from the restore-audit volume. (System managers can, however,
override this standard restore-and-purge mechanism by requesting TMF to retain
audit-trail files restored from tape on the restore-audit volume indefinitely, to enhance
performance.) For audit-trail files dumped to disk, TMF opens the disk-dump copy
directly without involving a restore-audit volume. More information about this recovery
operation appears under File Recovery on page 3-13.
Since restore-audit volumes are used only during recovery procedures, you can also
use restore-audit volumes as overflow volumes.