TMF Reference Manual (G06.26+)

TMFCOM Commands
HP NonStop TMF Reference Manual—522418-003
3-68
ALTER AUDITTRAIL
COMMITHOLDMODE and COMMITHOLDTIMER Option
Considerations
The COMMITHOLDMODE and COMMITHOLDTIMER options support the goal of Zero
Lost Transactions (ZLT) for customers using the HP NonStop™ Remote Database
Facility (RDF) subsystem to dynamically back up databases on remote systems. ZLT
is only possible with the RDF subsystem as implemented in the RDF/ZLT product,
working with the system’s disk process (DP2) and TMF transaction processing. (For
specific details about the RDF/ZLT product and its functionality, see HP NonStop
RDF/IMP, IMPX, and ZLT System Management Manual.)
The ZLT capability protects customers who cannot risk the loss of even a single
transaction during RDF takeover. The ZLT capability guarantees that, even if an outage
occurs, all transactions written to the audit trails on the source (primary) system will be
available on the remote (backup) system as well. Through the ZLT capability, no
transactions committed on the primary system are lost in the event of an RDF takeover
on the backup system.
Normally, if some or all of the resources needed to ensure ZLT on the backup system
become unavailable, transactions are nonetheless completed (committed or aborted)
on the primary system. In such a case, some transactions might not be copied to the
backup system and ZLT would not be fully achieved. However, by issuing the ALTER
AUDITTRAIL command with the COMMITHOLDMODE and COMMITHOLDTIMER
options, you can direct the TMP to stop writing audit (which includes transaction
commit and transaction abort records) to the audit trails on the primary system if such
an event occurs. (This deferral of audit is known as “activating commit-hold.”) In
addition, you can specify how long you want this deferral to continue.
Note. While commit-hold is activated, you cannot use the following TMFCOM commands:
•
ADD DATAVOLS, ALTER DATAVOLS, DELETE DATAVOLS, DISABLE DATAVOLS,
ENABLE DATAVOLS
•
ADD RESOURCEMANAGER, CLOSE RESOURCEMANAGER, DELETE
RESOURCEMANAGER
•
ABORT TRANSACTION, DELETE TRANSACTION, RESOLVE TRANSACTION
•
ALTER BEGINTRANS, DISABLE BEGINTRANS, ENABLE BEGINTRANS
•
ALTER TMF, SWITCHPROCESS TMP
•
STOP TMF
In addition, if commit-hold becomes activated for any audit trail while one of these commands
is executing, the command may hang until either the problem that activated commit-hold is
corrected, or until you suspend or turn off COMMITHOLDMODE.