Using Commitholdmode; Hardware Setup; Assigning Cpus On The Standby System - HP NonStop RDF J-series RVUs Management Manual

Using CommitHoldMode

If you want absolute ZLT protection, you must configure your audit trails with the
COMMITHOLDMODE attribute set to on. Doing so causes each write to the audit trail to be
directed to the remote audit trail disk first. If that write fails for any reason, TMF activates
commit-hold mode.
If CommitHoldMode mode is activated, TMF stops all further commit operations. Because
transactions on the primary system cannot commit or abort while the remote mirror is unavailable,
you achieve ZLT protection if you should lose your primary system while commit-hold mode
is activated. When such an event occurs, however, transaction processing on the primary system
effectively stops.
TMF provides another configuration attribute associated with CommitHoldMode:
COMMITHOLDTIMER. If CommitHoldMode is activated, the COMMITHOLDTIMER value
specifies how long you want CommitHoldMode to remain activated and what to do when that
time is reached. The parameters are:
COMMITHOLDTIMER {timeout [ON TIMEOUT {SUSPEND|CRASH}] | -1 }
If timeout is set to a positive value (from 5 seconds to 24 hours) and CommitHoldMode becomes
activated, all commit processing stops until either you correct the problem that caused activation
of COMMITHOLDMODE or the timeout value is reached. If the timeout value is reached, TMF
performs the action specified by the ON TIMEOUT option (SUSPEND or failure).
CommitHoldMode affects transaction processing on your primary system dramatically when a
remote mirror becomes unavailable. If a remote mirror becomes unavailable, you must choose
whether you want ZLT protection or the resumption of transaction processing.
If ZLT protection is critical to your disaster recovery plan, specify ON TIMEOUT CRASH.
Crashing TMF under these circumstances provides ZLT protection.
If it is important to resume transaction processing on the primary system, specify ON TIMEOUT
SUSPEND. Suspending commit-hold mode under these circumstances, however, deprives you
of ZLT protection should you lose the primary system to some unplanned outage.
If you set timeout to -1, TMF maintains an activated commit-hold state indefinitely until you
correct the issue causing the activation, you manually suspend commit-hold mode, or you turn
off commit-hold mode.
The default timeout value is 60 seconds and the default action upon reaching the timeout value
is SUSPEND (which means loss of ZLT protection).

Hardware Setup

To set up RDF for ZLT with remote mirror capability you must have established your hardware
setup first. That is, you must set up remote mirroring for every audit trail volume that relates to
the RDF environment before you configure RDF.
NOTE:
Because the remote mirrors will be connected to your standby system in the event of
an unplanned takeover, you should choose disk names that will not conflict with disks already
connected to the standby system.
ZLT is currently only supported with an HP StorageWorks XP disk array.

Assigning CPUs on the Standby System

By default, the same CPUs configured for each extractor on the primary system are used for the
corresponding extractor on the standby system, provided that both the necessary primary and
backup CPUs are available on the standby system.
If the necessary primary or backup CPU for an extractor is not available on the standby system,
the RDF monitor process selects from those CPUs that are available. If the monitor must select
340 Zero Lost Transactions (ZLT)