TMF Planning and Configuration Guide (G06.26+)

Reconfiguring Audit Trails

HP NonStop TMF Planning and Configuration Guide—522416-005

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Moving Data Volumes

As you gain experience with your application workload, you might need to load balance

your configuration by reassigning a data volume to another audit trail or by moving it to

another processor in your system.

To optimize the assignment of data volumes to audit trails, you should first gather

statistics about the major transactions in your application workload and which volumes

they update in the database. Identify which volumes are generating the highest audit

rates and spread these volumes among the auxiliary audit trails.

To reassign a data volume to another audit trail in the configuration, you might first

need to configure an additional auxiliary audit trail. This requires you to first stop TMF,

delete the TMF configuration, and restart TMF. Then you must do the following:

•

Disable the volume (so that it is in the disabled clean state) by using a DISABLE

DATAVOLS command.

•

Delete it from the configuration by using a DELETE DATAVOLS command.

•

Add the volume again by using an ADD DATAVOLS command, specifying another

audit trail with a lower audit rate.

•

If you are doing file recovery, immediately perform an online dump.

Moving a data volume to another processor is a complex operation that involves

physically moving the device and making system configuration changes. If you need to

move a data volume to another processor, contact your service provider for assistance.

To protect your database, you must always disable the volume (so that it is in the

disabled clean state) before you move it.

Changing the Overflow Threshold

The overflow threshold specifies, as a percentage of overall audit-trail capacity, the

point at which TMF copies the earliest audit-trail file from an active-audit volume to an

overflow-audit volume. The default overflow threshold is 80%.

You can change the overflow threshold while transaction processing is in progress by

using the OVERFLOWTHRESHOLD parameter of the ALTER AUDITTRAIL command.

Increasing the overflow threshold means that the audit trail will fill to a higher level

before TMF copies the earliest audit-trail file to an overflow-audit volume. If you set the

overflow threshold too high, there could be an interruption of transaction processing as

TMF waits for space to become available on the active-audit volume. For example, if

the overflow threshold is set to 95% and the audit trail fills to that level, it is possible

that the remaining 5% will not be enough to hold the audit information generated while

files are being copied to the overflow-audit volume. This could result in the audit trail

reaching its begin-transaction-disable threshold, thereby preventing new transactions

from starting.