HP NonStop RDF J-series RVUs Management Manual page 36

— A single primary system whose database changes are replicated to databases on multiple
backup systems. Such an environment makes possible simultaneous read-only access
to all of the backup databases (this is desirable for query-intensive applications such as
telephone directory assistance).
— Triple contingency—a special instance of the database replication feature whereby a
single primary system is protected by two identical backup systems. This feature allows
your applications to resume, with full RDF protection, within minutes after the loss of
your primary system, provided the two backup systems are not too far behind.
— Loopback configuration—where the primary and backup systems are the same system.
This has no value from a disaster protection standpoint, but can be useful for testing
purposes. Data from a set of volumes can be replicated to a different set of volumes on
the same node.
— RDF does not require an identical one-to-one volume relationship between volumes on
the primary system and those on the backup system. Backup volume names do not
have to match primary volume names. The subsystem can direct audit records from
more than one audited volume on the primary system to a single volume on the backup
system, provided that no more than one partition of a file exists on any backup volume.
(For information on partitioned files, see the Guardian User's Guide.)
• Application independence
RDF is application independent. It can protect through replication any audited NonStop
SQL tables and indexes as well as any audited Enscribe key-sequenced, relative, or
entry-sequenced files, including partitions, alternate key files, and Queue files. Unstructured
Enscribe files, however, are not supported.
36 Introducing RDF