Startupmsg; Autorestart; Disabling Lockstep; Reenabling Lockstep - HP NonStop RDF J-series RVUs Management Manual

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. 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
might 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 might or might 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.

Reenabling Lockstep

To reenable lockstep processing:
1. Change DISABLE to ENABLE 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 enabled.

Lockstep Performance Ramifications

By definition, a lockstep operation will increase the response time of your application because,
after having invoked DoLockstep, the application must wait for the data to become safely stored
in the backup system's image trail. The extractor and receiver processes have been streamlined
to facilitate lockstep processing, but a short delay is unavoidable.
Expand problems or CPU failures that trigger extractor and receiver restart operations could
also increase response times.
As described in
ever has a single lockstep transaction in progress at any one time. If called while a lockstep
"Multiple Concurrent Lockstep Operations" (page 312), the RDF gateway only
Disabling Lockstep 313