TMF Introduction (G06.24+)

TMF Overview

HP NonStop Transaction Management Facility (TMF) Introduction—522414-001

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Insurance Application Scenario

Problem: Communication Failure

An insurance agent at a remote site submits information on the sale of a new policy. A

fierce storm interrupts all communication lines so that the transaction cannot reach

headquarters to record information about the sale.

Solution: Transaction Backout

TMF detects that the headquarters system is not available and backs out all the

operations in the transaction to maintain database consistency. The insurance agent

does not have to worry about what part of the new policy was recorded: the agent just

has to wait until the required systems are available to resubmit the transaction about

the new policy.

Travel Agency Application Scenario

Problem: Stopping the System

The air conditioning fails in the computer room of a travel agency, and the room

temperature gets so hot that the computers have to be shut down to avoid physical

damage. The screens of all the agents using the system stop responding to input. All

the transactions in progress are interrupted.

Solution: Volume Recovery

Computer room personnel fix the air conditioning and cold load the system. Then the

database must be recovered. Recovery happens automatically when TMF is started.

The volume recovery process backs out any changes made by incomplete

transactions, which were all transactions in progress at the time of the shutdown.

Volume recovery puts the database online in a consistent state. The agents with

transactions in progress just before the shutdown must verify whether their

transactions completed, and resubmit any that were incomplete. The agents do not

have to be concerned about partially completed transactions because TMF ensures

either that the whole transaction is applied or that none of it is.

Manufacturing Application Scenario

Problem: Disk Volume Failure

In a manufacturing application, the head crashes on an unmirrored volume that stores

a portion of the local inventory database. The volume has to be replaced and

recovered.