RDF System Management Manual for J-series and H-series RVUs (RDF Update 13)

you might want to replicate $CAT.DSMCAT.* on the primary system to $DATA.DSMCAT.* on the
backup system. In that way replication of the DSM Tape Catalog and related files from the primary
to the backup system does not affect the DSM Tape Catalog and related files in $CAT.DSMCAT.*
on the backup system.
Views on the Backup System
If an application uses any NonStop SQL shorthand or protection views on a volume protected by
RDF, audit data for transactions on the views refers only to the underlying tables and not to the
views. Views and their underlying base tables must be present on the backup system after a takeover
operation so that applications can continue without interruption.
All base tables underlying the views must also reside on volumes protected by RDF on the primary
system.
Partitioned Tables and Files
If any partition of a partitioned NonStop SQL table or Enscribe file exists on a volume protected
by RDF, then all partitions for that file should be on volumes protected by RDF. The partitions of a
file protected by RDF can reside on separate systems, and all of the systems should be protected
by an RDF network. These are not absolute requirements, but if you lose your primary system and
must takeover on your backup system, you might not have access to the data that is not protected
by RDF.
Database Block Sizes and Cache on the Backup System
The block size of a file or table on your backup system must be identical to the corresponding size
of the file or table on the primary system. Failure to set proper block sizes on your backup system
can lead to unavoidable data corruption and failure. To ensure fastest RDF updater performance
configure as much cache for the block sizes of your database files as possible.
Specifying System Generation Parameters for an RDF Environment
When performing system generation:
• Use the PATHPACKETBYTES modifier to enable the Expand Variable Packetsize feature so
that Expand will send large packets.
• Use the CONGCTRL modifier to enable Expand congestion control.
• Use the AUDITTRAILBUFFER parameter to improve RDF extractor performance (set to the highest
value).
You might also want to enable the multipacket frame feature, depending upon the type of traffic
that will be passed over the Expand path.
For best results, consider using the RDF Professional Service to assist you in defining the Expand
requirements for your RDF environment. Contact your service provider for further details.
Designing Transactions for RDF Protection
When designing applications containing transactions that update databases protected by RDF,
you must consider the following restrictions that apply to the subsystem:
• The effects of network (distributed) transactions after an RDF takeover operation
• Database operations not replicated by RDF
The sections that follow explain these restrictions.
54 Preparing the RDF Environment