TMF Introduction (G06.26+)

TMF Overview
HP NonStop TMF Introduction—522414-002
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Database Recovery
TMF Transactions Are Permanent
Once a transaction is committed to the database, all the changes made by the
transaction remain in the database, despite any subsequent failure. TMF recovery
features ensure transaction permanence.
Database Recovery
TMF maintains the consistency of the database if a transaction fails to complete
successfully, even if any of the following failures or problems occur:
•
A TMF operator aborts a transaction that an application had previously initiated.
•
Program logic determines that an initiated transaction cannot complete and,
therefore, aborts the transaction.
•
Some single-component failure interrupts a transaction, causing it to be aborted:
for example, the processor that is processing the transaction fails.
•
Both disks of a mirrored pair fail while transactions are changing data on the disks.
•
The primary disk process controlling a disk fails while transactions are changing
data on the disk.
•
A system failure occurs because:
•
Multiple system components (processors or disks) fail and cause the entire
system to become unavailable.
•
An extended power failure or human error causes a total system failure.
TMF provides database recovery for failures ranging from a single-component failure
to a total system failure, using the following features:
•
Audit trails
•
Transaction backout
•
Volume recovery
•
Online dumps and audit dumps
•
File recovery