TMF Reference Manual (G06.26+)

TMFCOM Commands
HP NonStop TMF Reference Manual—522418-003
3-21
ADD AUDITTRAIL
When audit-trail overflow is triggered, TMF selects the overflow volume from among
those in the overflow-volume list for the audit trail. If the overflowing audit-trail file
resides on an active audit volume that is also configured as an overflow volume for that
audit trail, TMF tries to optimize overflow processing by using that same volume: TMF
just renames the overflowing file and preallocates a new audit-trail file. This same-
volume optimization greatly enhances overflow performance by eliminating the need to
copy the audit-trail file to another volume.
However, if TMF cannot perform same-volume optimization, TMF then searches the
overflow volume list serially to select an overflow volume, and copies the audit-trail file
to that volume.
RESTOREVOL Option Considerations
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.
BEGINTRANSDISABLE Option Considerations
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.
Other Operational Considerations
If the primary transaction management process (TMP) fails before the ADD
AUDITTRAIL command completes, the backup TMP takes over and undoes the effects
of that command before processing any new requests from TMFCOM. If both TMPs
fail before the ADD AUDITTRAIL command completes, TMF also undoes the effects of
that command.
If the ADD AUDITTRAIL command returns an error, files that were preallocated when
active volumes were added might not be purged from the volumes; this occurs if the
TMP loses access to these volumes. If you attempt to add these volumes as active
again with another ADD AUDITTRAIL command, the existing files are purged before
the new ones are created.
Caution. HP strongly recommends configuring each audit trail so that the same disk volume is
used as both the active-audit volume and the overflow volume, permitting same-volume
optimization. If you do not configure the audit trail in this way, transaction throughput can be
severely degraded when overflow processing occurs.