RDF System Management Manual

Zero Lost Transactions (ZLT)
HP NonStop RDF System Management Manual—524388-003
16-6
Hardware Setup
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.
Note that 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.
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 the primary CPU for all extractors, it puts the primary processes of
the extractors in as many different CPUs as possible to achieve load balancing;
however, only if there are enough CPUs. If, for example, you have six extractors
configured, but you only have two CPUs on your standby system, the monitor places
the primary processes of three extractors on one CPU and the primary processes for
the other three extractors on the other CPU. Note that if the monitor process selects
the primary CPU of an extractor and the configured backup CPU is not available on the
standby system, then the extractor does not run as a process pair; it only has the
primary process.
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.