TMF Operations and Recovery Guide (G06.24+)

Occasional Operations
HP NonStop TMF Operations and Recovery Guide—522417-002
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Changing the Autoabort Configuration
data volume. This kind of maintenance should be performed when there is little or no
transaction activity.
When you need to disable new transactions, use the DISABLE BEGINTRANS
command. After you issue a DISABLE BEGINTRANS command, TMF continues to
process existing transactions, but prevents new transactions from beginning. You can
still use the TMFCOM commands for dumping files, adding tape volumes to the
catalog, recovering files, obtaining information about dumps and TMF status, and so
forth.
New transactions cannot begin until an ENABLE BEGINTRANS command is issued.
Changing the Autoabort Configuration
The TMF autoabort function automatically aborts transactions if they run longer than a
set amount of time. This feature is useful in an online transaction processing
environment where the transactions are usually short, and long-running transactions
are assumed to be “runaways.” Since long-running transactions are identified and
automatically aborted, you can turn off the autoabort function if you know that there are
going to be many long-running transactions.
The time limit used to identify long-running transactions is known as the autoabort
threshold. This threshold specifies the length of time that a transaction can run before
TMF automatically aborts it. By default, the autoabort threshold is two hours.
Autoabort Threshold
Increasing the autoabort threshold means that transactions can run longer before TMF
automatically aborts them. Consider increasing this threshold if you notice that TMF is
frequently aborting transactions and the active capacity of the audit trail is well below
the overflow threshold. If the audit trail is near its overflow threshold, increase the size
of the audit trail before you increase the autoabort threshold. TMF performance is
better when TMF is not frequently interrupted to back out transactions.
Decreasing the autoabort threshold means that TMF aborts transactions sooner.
Consider decreasing this threshold when transaction durations are normally shorter
than the autoabort threshold, or when you want runaway transactions to be aborted
sooner.
Caution. Disabling new transactions stops transaction processing on your system. This
action will probably cause your transaction processing applications to fail, so you should stop
your applications before disabling transactions. If you must disable new transactions, choose
a time when the interruption will affect system users the least.
Note. If transactions run too long, the audit trail can reach its overflow threshold and,
eventually, can reach its begin-transaction-disable threshold.