RDF/IMP and IMPX System Management Manual (RDF 1.4+)

Triple Contingency
HP NonStop RDF/IMP and IMPX System Management Manual—524388-001
10-3
Software Requirements
Software Requirements
You must be running the same release of RDF on all three systems (the primary
system and both backup systems).
The two RDF subsystems should be configured identically with respect to both backup
systems.
At the very least, the following key fields must be identical on both backup systems:
•
The primary database volumes being protected
•
The mapping of data volumes between the primary and backup system
•
The number of image trails
•
The mapping of updaters to image trails
•
The image trail extents
•
The purger RETAINCOUNT
Other fields, such as process names and process priorities, do not need to be identical
on the two backup systems.
It is strongly recommended, however, that the various RDF process priorities be
identical on both backup systems so that the performance of the two systems is
approximately the same.
WARNING. If the two backup systems are configured differently from one another in any
important regard, the triple contingency feature will not work when you need it, and there will
be no advance warning to that effect. Prior to a primary system failure, the two backup
systems run independently of one another and no cross-checking whatsoever is performed to
verify that they are configured compatibly for triple contingency recovery.
To guarantee that the two backup systems are configured compatibly, it is strongly
recommended that you FUP DUP the OBEY command file that you use for initializing and
configuring one RDF configuration, change the suffix character and the backup system in the
INITIALIZE RDF command (and perhaps some of the process names), and then use that same
OBEY command file to initialize and configure the second RDF configuration.