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

SYNCHDBTIME Issues
With the SYNCHDBTIME option in the INITIALIZE RDF command, there are three special cases
you might need to consider:
• Enscribe create operations
• NonStop SQL/MP Shared Access DDL operations
• TMF shutdown operations
Enscribe Create Records
If you created the same Enscribe file on the primary and backup systems prior to execution of
the INITIALIZE RDF command, and if the extractor’s restart position is located before the audit
record for the create operation on the primary system, you must remember to purge that file on
the backup system. Otherwise, when the updater tries to replicate the create operation, it will
report a File System error 10 (File Already Exists) and restart. It continues to restart and attempt
to create the file until you purge the existing file on the backup system.
Stop-RDF-Updater Records
Stop-RDF-Updater records in the MAT are associated with committed NonStop SQL/MP DDL
operations performed on the primary system with the WITH SHARED ACCESS option. Although
such operations can be performed on the primary system without stopping your applications,
they must be performed manually on the backup system after all updaters have shut down in
response to the same Stop-RDF-Updater record.
As a general rule, you should not initialize the RDF subsystem to a synchdbtime if you recently
performed a NonStop SQL/MP operation with SHARED ACCESS on the primary system. For
example, suppose you have a NonStop SQL/MP table (tableA) that contains the range of keys
A through Z and you just moved its partition boundary such that tableA now contains only
the keys A through M and a new table (tableB) contains the keys N through Z. Suppose also
that you performed this operation manually on the backup system.
If you then initialize the RDF subsystem to a point in the MAT prior to the Stop-RDF-Updater
record associated with the partition boundary change and an updater encounters audit information
associated a key N through Z, the updater will report an error because it will try to apply the
audit information to tableA (which used to contain it, but now does not), and the audit
information will not be applied to the backup database. In this particular case the database is
not corrupted, but data corruption could occur for other NonStop SQL/MP DDL SHARED
ACCESS operations.
If you did recently perform a NonStop SQL/MP operation with SHARED ACCESS on the primary
system and you want to initialize the RDF subsystem to a synchdbtime, you must specify a
synchdbtime such that the starting position in the MAT is after the Stop-RDF-Updater record.
As a precaution, if RDFCOM encounters a Stop-RDF-Updater record during its backward search
of the MAT, it issues a warning message to that effect asking if you want to proceed with
initialization. If the extractor encounters such a record while operating in database synchronization
mode, it abends.
TMF Shutdown Records
TMF shutdown records in the MAT do not cause a problem, except that RDF shuts down and
you must then restart it.
CREATE/LOAD Issues
The LOAD command only works on tables and files that are nonaudited. If you create the empty
duplicate tables and files as audited entities, you must then use FUP ALTER commands to turn
off their audit attributes before you can load them.
158 Online Database Synchronization