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

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.
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.
Replicating Database Operations
Database administrators preparing to work with RDF should be aware of considerations
concerning:
• NonStop SQL/MP and NonStop SQL/MX Data Definition Language (DDL) operations
• NonStop SQL/MP and NonStop SQL/MX DDL operations with Shared Access
• Enscribe file-label modifications
• Purge operations
• Partitioned files
• Temporary disk files
NonStop SQL/MP and NonStop SQL/MX DDL Operations
Although RDF replicates NonStop SQL/MP and NonStop SQL/MX Data Manipulation Language
(DML) operations, it does not replicate NonStop SQL/MP and NonStop SQL/MX Data Definition
Language (DDL) operations except for PURGEDATA. Excluding PURGEDATA, the database
administrator needs to perform all other DDL operations (such as CREATE TABLE or CREATE
INDEX) manually on the backup system as well as on the primary system.
User programs cannot create audited NonStop SQL/MP and NonStop SQL/MX tables and write
to them without coordinating table creation on the primary system with table creation on the
backup system.
Recommended procedures for performing NonStop SQL DDL operations in an RDF environment
are described in “NonStop SQL/MP or NonStop SQL/MX Databases” (page 149).
Enscribe File-Label Modifications
In general, RDF does not replicate Enscribe file-label modifications.
Preparing Software and Database Files for RDF Operations 69