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

Managing RDF
Compaq NonStop™ RDF/IMP and IMPX System Management Manual—522204-001
5-11
Stopping RDF
Stopping RDF
If the communications lines between the primary and backup systems are up, there are
two ways to stop RDF:
1. Issue a STOP RDF command on the primary system.
2. Issue a TMFCOM STOP TMF command on the primary system. After the RDF
updaters have reached the TMF shutdown record, RDF stops and then TMF stops.
If the communications lines between the two systems are down and you want to stop
RDF, you must issue the STOP RDF command on both the primary and backup systems.
For each shutdown procedure, the RDF receiver and updater processes write their
current context information to the RDF context file before stopping. If you restart but do
not reinitialize RDF, the product retrieves the context information from the context file.
The context information enables the RDF processes to resume processing where they
stopped before the shutdown, unless an audit trail file that RDF needs has been purged
and cannot be restored to disk.
Stopping RDF by Stopping TMF
The reason for stopping RDF by stopping TMF is to ensure that the primary and backup
databases are logically identical when the shutdown is complete (RDF has applied all
changes to the backup database). That will be the case, of course, only if all the updater
processes stopped at the shutdown record (if an updater experiences a double CPU
failure, the databases will not be identical). The disadvantage of this approach is that all
applications on the primary system that use TMF must be stopped also.
When you issue a TMFCOM STOP TMF command, the following events occur:
1. TMF writes a shutdown record to the MAT. When the extractor reads the shutdown
record, it notifies the monitor that TMF has stopped.
2. If updating is enabled, each updater process stops when it reaches the TMF
shutdown record in its image trail.
3. The receiver stops when all updater processes have stopped.
4. The extractor stops as soon as the receiver replies that it has processed the TMF
shutdown record.
5. The monitor stops after all the other RDF processes have stopped.
Note. If the extractor process falls way behind TMF because the communications lines to the
backup system have been down and come up again, it can take some time for the extractor to
get to the TMF shutdown record. The extractor stops processing the audit trail files when it
cannot communicate with the receiver and resumes processing when the communications
lines are restored.