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

Managing RDF
Compaq NonStop™ RDF/IMP and IMPX System Management Manual—522204-001
5-13
Stopping RDF From the Backup System
To leave the two databases logically identical, you must do the following before issuing
the STOP RDF command:
•
Issue a TMFCOM DISABLE BEGINTRANS command. This command prevents
the applications from initiating any new transactions until you issue a TMFCOM
ENABLE BEGINTRANS command.
•
Issue TMFCOM STATUS TRANSACTIONS commands and wait until the display
shows no transactions in progress.
•
Issue STATUS RDF commands and wait until all of the RDF Time Delay (RTD)
times are zero.
•
Issue the STOP RDF command.
(For an alternate method of bringing the backup database to a consistent state, see
Access to Backup Databases in a Consistent State
later in this section.)
When you issue a STOP RDF command from the primary system, the following events
occur:
1. RDFCOM sends a STOP message to the monitor.
2. The monitor sends stop messages to the extractor, the receiver, the purger, and all of
the updater processes.
3. The monitor stops after all RDF processes have stopped.
If the communications lines between the two systems are down when you issue the
STOP RDF command, the monitor tells the extractor to stop and writes an error message
for every process running on the backup system that the monitor could not access; the
monitor then stops itself. If this situation occurs, you must use RDFCOM on the backup
system to stop the remaining RDF processes before you can restart RDF.
Stopping RDF From the Backup System
If you issue a STOP RDF command on the primary system when the communications
lines are down, then you must also do so on the backup system. That is the only time
you should ever issue a STOP RDF command on the backup system.
RDF can recover from a communications line failure, as explained under Responding to
Operational Failures earlier in this section.
When you issue a STOP RDF command on the backup system, RDFCOM attempts to
contact the RDF monitor on the primary system. After discovering that the monitor is
not accessible, RDFCOM sends individual stop messages to all RDF processes on the
backup system.
Caution. If the starting of new transactions is disabled, applications could abort unless they
have been coded to handle that situation.
Note. Even when no TMF transactions are in progress, TMF periodically writes control points
to the MAT, which means that the MAT continues to fill even when no application activity is
occurring. This can cause RTD times in the status display to fluctuate.