TMF Planning and Configuration Guide (H06.06+, J06.03+)

Reconfiguring Audit Trails
HP NonStop TMF Planning and Configuration Guide—540136-005
3-7
Increasing Audit-Trail Throughput
The 45% value cannot be changed in the configuration. If this feature causes TMF to
abort transactions that should not be aborted, you must increase the audit-trail capacity
by either increasing the number of audit-trail files per volume or by adding another
active-audit volume. When the additional audit-trail space is no longer needed, you can
reduce the audit trail to its original size.
In addition, TMF has an autoabort threshold based on a configurable transaction
timeout value.
If any audit-trail sequence number is 900,000 or more, TMF must be stopped and re-
configured with larger audit-trail sizes in the near future. TMF will stop abruptly, and
cannot be restarted, at the rollover of the audit trail (master of auxiliary) after the
999,999th audit trail is filled.
Increasing Audit-Trail Throughput
There are two situations in which disk head contention could arise and affect TMF
performance:
1. During audit dumping, if there is only one active-audit volume
2. During file recovery, if a restore-audit volume and active-audit volume are
configured on the same physical disk drive
For the first type of contention, you can either manually defer audit dumping to a later
time with a DISABLE AUDITDUMP command (as described in Pausing and Resuming
Audit Dumping on page 5-9) or add another active volume with an ADD AUDITTRAIL
Caution. Online resizing of audit trails might cause severe performance degradation, if the
global Safeguard attribute CLEARONPURGE-DISKFILE is set to ON. The system may freeze for
a few minutes, and then recovers.
To avoid performance degradation when the global Safeguard attribute CLEARONPURGE-
DISKFILE is set to ON, perform the following steps during audit trails resizing:
1. Select a period of low transactional activity to perform an online resize of audit trail(s).
2. Set the global Safeguard attribute CLEARONPURGE-DISKFILE to OFF.
3. Complete one of the following sequence of steps:
a. Re-size the audit trail file(s).
b. Issue the NEXT AUDITTRAIL command against the resized audit trail(s) until those
audit trail file(s) are recreated with the new file size.
OR
a. Change the format of the audit trail file(s) from format 1 to format 2 or from format 2 to
format 1.
b. Issue the NEXT AUDITTRAIL command against all the audit trail(s) until those audit
trail file(s) are recreated with the new format.
After resizing or reformatting the audit trail files, set the global Safeguard attribute
CLEARONPURGE-DISKFILE back to ON.