RDF/IMP and IMPX System Management Manual (RDF 1.3+)

Lockstep Operation
Compaq NonStop™ RDF/IMP and IMPX System Management Manual—522204-001
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PROGRAM
PROGRAM
This attribute specifies where the RDF gateway object code resides. Typically, that
location is the same volume and subvolume where all of the other RDF software resides.
Note that the object name is LSGO, and that you must fully qualify the name. For
example, you might specify the PROGRAM attribute as $SYSTEM.RDF.LSGO.
STARTUPMSG
This attribute must include the process name of your RDF extractor (for example,
STARTUPMSG "ENABLE $MEXT"). The startup message must also include either
ENABLE or DISABLE as the first parameter. Failure to include either of these
parameters will cause the gateway to stop. Note that the gateway can only communicate
with one extractor. If you have multiple RDF subsystems using the same node as their
primary system, only one of them can execute lockstep operations.
AUTORESTART
This attribute specifies the number of times SCF attempts to restart the gateway process
if it should stop unexpectedly. You should set this attribute to 10.
Disabling Lockstep
To disable lockstep processing:
1. Change ENABLE to DISABLE in the STARTUPMSG attribute script.
2. Manually delete the RDF lockstep gateway process from SCF.
3. Run the changed SCF script.
When SCF restarts the gateway, lockstep processing is disabled. Thus, if your
application calls DOLOCKSTEP, the gateway will return control immediately to the
application without doing lockstep processing.
Disabling lockstep processing is a very useful feature. Suppose that the communications
lines from your RDF primary to your RDF backup systems are down. In such a case,
the extractor cannot send audit data to the backup system, and lockstep processing will
hang until the communications lines are back up and the extractor resumes sending audit
data. This is desired behavior if you really want lockstep processing. But suppose that
the communications lines have been down for so long that your applications are getting
no work done at all. In such a case, you may want to disable lockstep processing to
allow your applications to resume their work without lockstep operations.
When lockstep is disabled, remember that your original transaction has already
committed on the primary system. If you should subsequently lose the primary system
and do a takeover on the backup system, the transaction may or may not have been
committed in the backup database depending on whether or not the extractor got all of
the original audit data over to the backup system before the primary system failed.