TMF Reference Manual (G06.24+)

TMFCOM Commands
HP NonStop TMF Reference Manual—522418-002
3-18
ADD AUDITTRAIL
related to sets of data volumes. Each auxiliary audit trail is uniquely identified by the
prefix AUX followed by a two-digit number: for example, AUX03.
For attributes not specified in the ADD AUDITTRAIL command, you can assign values
by entering SET AUDITTRAIL commands earlier in the same TMFCOM session;
otherwise, the default values, if they exist, are used.
Before it takes effect, the ADD AUDITTRAIL command verifies that the volumes
specified do not contain any files in the ZTMFAT subvolume, which is reserved for use
by audit trails created under the current TMF configuration. You can use the DELETE
TMF command to purge any audit-trail files left over from a previous TMF
configuration.
TMF uses the FILESPERVOLUME value to pre-allocate the number of files in the
active-audit trail that reside on each volume; if they cannot all be allocated, the ADD
AUDITTRAIL command fails. You can change the FILESPERVOLUME value by using
the ALTER AUDITTRAIL command, whether TMF is started or not.
TMF calculates disk extent size on the basis of 16 extents per file, with all extents (both
primary and secondary) being the same size.
Overflow-audit volumes are used to store files when the active-audit trail becomes too
full. At this point, the oldest audit-trail files are copied to the overflow volumes so that
the space occupied by these audit-trail files can be reused. In the OVERFLOWVOLS
parameter, you can specify the overflow-audit volumes you want TMF to use for this
purpose. In the OVERFLOWTHRESHOLD parameter, you can specify the capacity
level of the active-audit trail that will trigger overflow copying. For example, if you want
overflow copying to begin when 95% of the available audit trail space has been used,
set OVERFLOWTHRESHOLD to 95. The time it takes to reach the overflow threshold
depends on the audit generation rate and the total audit trail capacity.
Once overflow copying begins, it continues until the capacity used falls below the
threshold, even though space subsequently becomes available on the active-audit
volume. When they are no longer needed, overflow files are automatically purged by
TMF.
Restore-audit volumes are used to receive audit-trail files restored from an audit dump
as part of a recovery procedure. You can specify the restore-audit volumes associated
with the audit trail through the RESTOREVOLS parameter.
Configuring an active-audit volume as an overflow- or restore-audit volume might result
in contention for the disk, adversely impacting performance. To avoid this, you should
consider disk capacity, available free space, and probable audit activity when
configuring.
Another attribute related to audit trail capacity is the BEGINTRANSDISABLE
parameter. This value indicates the percentage of audit trail capacity that can be
consumed before TMF automatically disables new transactions. This value must be
low enough to ensure that existing transactions have enough room in the active-audit
trail for completion. The appropriate value depends on the transaction load, the
demands of the applications, and other factors prevailing in the system.