SQL/MP Installation and Management Guide

Planning Database Security and Recovery
HP NonStop SQL/MP Installation and Management Guide—523353-004
4-14
Guidelines for Configuring TMF
backs out event records, thereby eliminating valuable historical information about
events such as failures.
A database with a combination of audited and nonaudited tables can be left in an
inconsistent state after a failure. If a failure occurs, audited tables are recovered to the
original state, but updates to nonaudited tables are left in an unknown state. You will
need a strategy to recover the nonaudited tables so that the database will be
consistent.
The default volume for the system catalog is $SYSTEM. If you intend to use this
default volume, $SYSTEM must be audited.
Determining a Level of Data Protection
Configure the TMF subsystem for the level of protection your application needs. The
minimum level of protection uses the automatic recovery features of TMF backout and
volume recovery. Audit dumps and online dumps allowing for file recovery are optional.
After you determine the level of protection you need, configure the TMF subsystem
accordingly.
Size Considerations
When determining the size requirements of the TMF subsystem for SQL/MP, consider
these:
•
The catalogs are audited tables; therefore, insertions and updates to catalogs are
audited.
•
DDL statements run within system-defined TMF transactions, generating audit-trail
entries. DDL statements that refer to large tables can generate a large volume of
audit-trail entries.
•
Transaction volume includes database use by both application programs and
SQLCI interactive capabilities. The interactive volume might be minimal or might
generate many audit-trail entries.
•
You should estimate insert, update, and delete transaction activity for each table
and view.
•
If parallel update and delete operations are being done, consider increasing the
amount of audit trail space available to TMF. For more information, see the TMF
Operations and Recovery Guide.
•
For Enscribe systems being converted to use SQL/MP, you might need to increase
the size of TMF audit trails to accommodate the catalog auditing and database
manipulation activity.
•
To prevent suspension of TMF transactions, you should have at least two tape
drives available. If you have only one tape drive and the drive fails, the TMF
subsystem suspends all new transactions if the maximum number of files is
reached.