RDF/IMP and IMPX System Management Manual (RDF 1.3+)

Managing RDF
Compaq NonStop™ RDF/IMP and IMPX System Management Manual—522204-001
5-29
Exception File Optimization
If you have configured an RDF network to replicate network transactions, a considerable
amount of undo could also be required if any of the nodes in the network falls behind the
others prior to a takeover.
In any case, if an updater has a large number of audit records to undo during a takeover,
the performance of its undo pass is negatively affected by logging exception records.
Therefore, with version 1, update 2 of the RDF/IMP and IMPX products the manner in
which exception files are used is now a configurable attribute.
To set this attribute, use the following RDFCOM command:
SET RDF UPDATEREXCEPTION {ON | OFF}
When this attribute is set to ON (the default value), the updater logs an exception record
for every audit record it must undo during a takeover.
When this attribute is set to OFF, the updater logs exception records only for the first
and last audit records that must be undone (the minimum logging necessary to support
Triple Contingency operation).
Note. The ZTXUNDO and the ZNETUNDO files list the transids of all transactions that must
be undone. Therefore, using the RDIMAGE tool, you can still examine all of the audit records
that were undone even if you have UPDATEREXCEPTION is set to OFF.