RDF System Management Manual for H-Series RVUs (RDF 1.8)

More specifically, the updates for a transaction on one of the two primary systems might have
been successfully transmitted and applied to the associated backup database, but a disaster
brought down the other primary system before the updates by the transaction on that system
could be sent to its backup database. After executing RDF takeover operations on both backup
systems, the data from the network transaction would be present in one backup database but
not in the one brought down by the disaster. Thus the distributed backup database is inconsistent
with regard to the affected network transaction.
For information about this capability, see Chapter 14 (page 275).
RDF and NonStop SQL/MX
RDF can replicate NonStop SQL/MX user tables and indexes as well as NonStop SQL/MP objects
and Enscribe files.
For information about this capability, see Chapter 16 (page 295).
Zero Lost Transactions (ZLT)
Zero Lost Transactions (ZLT), which is available only with the RDF/ZLT product, is a functional
capability that uses mirrored disks to guarantee that no committed transactions on the primary
system will be lost in the event of an RDF takeover by the backup system.
For information about this capability, see Chapter 17 (page 309).
Monitoring RDF Entities With ASAP
ASAP (Availability Statistics and Performance) allows many different subsystem entities to be
monitored across a network of NonStop servers. The status and statistics for the entities are
collected on a single system, and are then monitored either through the ASAP command interface
or through the ASAP graphical user interface PC client.
RDF/IMP, IMPX, and ZLT are instrumented to feed state information to ASAP, thus allowing
RDF subsystems to be monitored, in an integrated way, alongside all other subsystems supported
by ASAP. The following RDF entities report state and statistical information to ASAP:
• Monitor
• Extractor
• RDFNET (optional)
• Receiver
• Purger
• Updater
For information about using ASAP to monitor RDF entities, see Appendix E (page 439).
62 Introducing RDF