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

Preparing the RDF Environment
HP NonStop RDF/IMP and IMPX System Management Manual—524388-001
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Disk Volume Limit
is identical to that of the primary system, your system personnel can adjust more
quickly to the backup environment during disaster recovery.
If you cannot configure the backup system as an identical copy of the primary system,
plan the configuration of the backup system with enough processing power and disk
drives to enable RDF to keep the backup database current with the primary database.
Because RDF only applies database modifications on the backup system, the CPU
requirements on the backup system when running RDF will typically be lower than the
total CPU requirements on the primary system running the applications. The actual
backup CPU requirements depend on many factors, including the RDF configuration,
the rate of audit transmission from the primary system to the backup system, the
database update rate, and whether or not you have copies of your applications
installed (in “standby” mode). Remember that updaters now apply changes to the
backup database in transaction mode, which will also draw on the CPU capacity of the
backup system.
Sizing the RDF configuration is a complex task that is best carried out by HP
personnel. Those personnel can assist you in configuring and sizing your RDF
environment using tools and utilities designed and developed as part of the RDF
Professional Service.
Contact your service provider for further details.
Disk Volume Limit
The RDF/IMP and IMPX products can protect up to 255 physical or virtual volumes on
your primary system, and the updaters for these volumes replicate to either a single
physical or virtual disk on the backup system.
Volume-to-Volume Mapping
The recommended disk drive configuration for RDF products is a one-to-one mapping
between the primary volumes and their corresponding backup volumes, with mirrored
disks on both systems. This one-to-one mapping ensures that each partition of a
partitioned file or table is mapped appropriately to a backup volume.
Volume names on the backup system can differ from those on the primary system, but
the use of identical primary and backup volume names prevents naming conflicts after
a takeover operation. If the names of the backup volumes are different than those of
the corresponding primary volumes, you will need to change all volume references
before the primary system’s applications can start on the backup system.
For more information about takeover operations, see “Initiating Takeover Operations” in
Section 5.