SQL/MP Installation and Management Guide

Planning Database Security and Recovery
HP NonStop SQL/MP Installation and Management Guide—523353-004
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SQL Requirements for TMF
The TMF subsystem handles backout operations without operator intervention by using
the audit trails automatically cycled by the TMF subsystem. The TMF backout process
uses before-images in the audit trails to undo the effects of an aborted transaction.
Volume Recovery
Volume recovery recovers the database in the event of a disk crash or system failure.
When the TMF subsystem is restarted after a failure, volume recovery is initiated
automatically for each accessible data volume on the system (except for volumes
explicitly disabled in TMF).
To recover the files, the volume recovery process re-applies committed transactions to
ensure they are reflected correctly in the database, and then backs out all transactions
that were incomplete at the time of the interruption.
File Recovery
File recovery reconstructs specific audited files when the current copies on the data
volume are not usable: for example, if a system or media failure jeopardizes the
consistency of one or more audited files. A file could require file recovery for one or
more reasons, including:
•
A disk failure (irreparable media failure) occurs.
•
A volume or system failure occurs, and volume recovery cannot recover the file.
•
A file is mistakenly purged.
•
An application program incorrectly changes the database.
File recovery includes restoring online dumps from tape to disk, applying the after-
images from the audit trail to the database records, and then backing out all
transactions that were incomplete at the time of the system interruption or failure.
SQL Requirements for TMF
To protect the data dictionary in recovery situations, SQL/MP requires auditing of the
SQL catalogs by the TMF subsystem.
(Similarly, volumes that contain SQL objects, except programs, must be enabled for
auditing by the TMF subsystem.) Individual SQL tables, indexes, and views can be
nonaudited; however, both audited and nonaudited objects must reside on audited
volumes because the file labels are audited.
SQL catalogs, tables, views, indexes, collations, and partitions of tables and indexes
must reside on volumes enabled for auditing by the TMF subsystem. (Similarly,
volumes that contain SQL objects, except programs, must be enabled for auditing by
the TMF subsystem.)
Individual SQL tables, indexes, and views can be nonaudited, although both audited
and nonaudited objects must reside on audited volumes because the file labels are