TMF Reference Manual (G06.26+)

TMFCOM Commands
HP NonStop TMF Reference Manual—522418-003
3-65
ALTER AUDITTRAIL
MAXRETAINEDATFILES Option Considerations
During volume recovery or file recovery, 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. When the recovery process
completes, TMF purges this file and all other unneeded files from the restore-audit
volume. When TMF is processing multiple recovery operations, whether serially or in
parallel, a recovery process often must wait for TMF to restore the audit-trail file
repeatedly to support each recovery operation.
By entering the ALTER AUDITTRAIL command with the MAXRETAINEDATFILES
option, you can override this standard restore-and-purge mechanism so that TMF
keeps audit-trail files restored from tape on the restore-audit volume indefinitely. This
option greatly enhances performance by:
•
Eliminating or minimizing the time a recovery process must wait for TMF to restore
an audit-trail file.
•
Minimizing disk contention for audit-trail files being read from, or restored to, the
same disk.
Use the MAXRETAINEDATFILES option when you expect to conduct many recovery
operations at or near the same time, keeping as many potentially required files on disk
as possible. When the recovery load diminishes, use the RESET
MAXRETAINEDATFILES option to return to the standard restore-and-purge
mechanism for tape files, freeing disk space for other purposes. Remember:
MAXRETAINEDATFILES optimizes access time for files archived on tape; RESET
MAXRETAINEDATFILES maximizes available disk space.
For audit trails restored from tape, MAXRETAINEDATFILES allows you to specify the
amount of disk space available for retaining audit files in terms of the number of files.
If you enter MAXRETAINEDATFILES while TMF is running, this option takes effect
immediately. If you enter MAXRETAINEDATFILES while TMF is stopped,
MAXRETAINEDATFILES takes effect when TMF restarts. The
MAXRETAINEDATFILES integer value specifies the number of audit-trail files to be
retained. This value applies only to the audit trail specified in the current ALTER
AUDITTRAIL command; TMF manages each audit trail individually with regard to its
MAXRETAINEDATFILES attribute.
The integer value specifies the total number of audit-trail files retained across the
entire set of restore-audit volumes. In other words, whether you have one restore-
audit volume or five restore-audit volumes, setting the value to 50 would give you a
maximum of 50 retained audit-trail files in either case.
Note. For audit-trail files dumped to disk, TMF opens the disk-dump copy directly, rather than
copying it to a restore-audit volume. Therefore, for audit-trail files on disk, the entire disk-
restore time is eliminated and all recovery processing (even the first) need not wait for this
restore operation. Therefore, you do not specify MAXRETAINEDATFILES for audit-trail files on
disk.