Pathway/iTS TCP and Terminal Programming Guide

Managing Transactions With the TMF Subsystem

Compaq NonStop™ Pathway/iTS TCP and Terminal Programming Guide—426751-001

5-13

Precautions for Using TMF Parameters

If a TMF error occurs and makes normal operation impossible, you should not try to

solve the problem by setting the PATHCOM TMF parameter options to OFF. Setting

these options to OFF can have the following results:

•

A server intended for operation with TMF protection probably does not send the

checkpoint messages necessary to function as a fault-tolerant server when the TMF

subsystem is not invoked.

•

A SCREEN COBOL program that uses ABORT-TRANSACTION or RESTART-

TRANSACTION statements to handle exceptions to normal program operation only

appears to execute; the ABORT-TRANSACTION or RESTART-TRANSACTION

statements have no effect.

•

With the SET SERVER TMF parameter defined as ON and the SET TERM or SET

PROGRAM TMF parameters defined as OFF, the TCP sends checkpoint messages,

performs retries, and sets the sync depth as if the TMF subsystem were running. For

example, the TCP performs fewer checkpoints and opens servers with a sync depth

of 0 instead of 1. In this case, the TCP does not take full advantage of fault

tolerance, and a single CPU failure can cause the application to fail.

Refer to the NonStop™ TM/MP Operations and Recovery Guide to determine how to

address the TMF error.