TMF Operations and Recovery Guide (G06.24+)

HP NonStop TMF Operations and Recovery Guide—522417-002
7-1
7 Recovery Methods
TMF automatically protects your database with its backout and volume recovery
processes. You can perform file recovery on your database, if necessary, as long as
you have routinely done online dumps and audit dumps.
This section discusses how TMF recovery processes work and gives examples of how
to recover from or prevent a variety of situations that could damage your database. It
covers the following topics:
You can use the TMFCOM command interface to perform TMF recovery operations, as
illustrated by the procedures described in this guide.
Transaction Backout
The backout process is automatic to your TMF system; it is started when you start
TMF, and is terminated when you stop it. You do not have to invoke it, but it is helpful
to understand how the process works so you can interact with it in special
circumstances.
The backout process undoes the database changes made by a transaction that did not
complete (an aborted transaction). Backout is invoked automatically when a
transaction enters the aborting state. A transaction enters the aborting state for one of
the following reasons:
•
The process controlling the transaction calls the ABORTTRANSACTION
procedure.
•
The process controlling the transaction terminates while the transaction is active.
•
A server working on the transaction fails, or a process cancels a request to a
server before the server replies.
•
The transaction exceeds the autoabort threshold.
•
The transaction is specified in an ABORT TRANSACTION command.
•
The transaction is specified in a RESOLVE TRANSACTION command with the
STATE ABORTED option.
Topic Page
Transaction Backout 7-1
Volume Recovery 7-3
File Recovery 7-7
Retaining Audit Files Restored from Tape on Restore-Audit
Volumes
7-19
Recovering Audit-Trail Files Dumped to Disk 7-20
Recovery Scenarios 7-20