RDF System Management Manual for J-series and H-series RVUs (RDF 1.10)

(that is, which system had received the least amount of audit data from the extractor by the
time the primary system was lost).
• On the backup system that was further behind (had the least amount of audit data), issue the
COPYAUDIT command specifying the name of the other backup system and its RDF control
subvolume. That command copies over all missing audit records from the designated system.
• Upon successful completion of the COPYAUDIT operation, do a second takeover on that
system. When the second takeover has completed successfully, initialize and configure the
two backup systems as a new primary-backup pair (either system can be the primary) and
then restart application processing on the new primary system.
The remainder of this chapter discusses the hardware and software requirements, the RETAINCOUNT
parameter, and the COPYAUDIT command in detail.
WARNING! To be able to use the triple contingency feature, it is imperative that you carefully
obey the instructions and caveats presented in this chapter.
Hardware Requirements
Both backup systems should have similar hardware with respect to RDF operation (in particular,
the data volumes and image trails must be identical between the two systems). It is also strongly
recommended that the Expand bandwidth between the primary and backup systems be the same
for both configurations, as well as between the two backup systems.
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, these 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.
Hardware Requirements 261