Advanced Topics › How You Influence Device Selection › Using Exit Routines to Influence Device Selection

Using Exit Routines to Influence Device Selection

TPCF provides three exit routines that you can use to influence device selection during allocation and allocation recovery:

TPCEDLXT

TPCF uses elimination logic to mark devices ineligible in the EDL early in the z/OS allocation process. Therefore, you can use this routine to unconditionally prevent devices from being candidates for allocation.

TPCRECXT

Customizes the TPCF processing of allocation recovery messages. You can use this routine to address site-specific process needs that are not completely served by the CA MIA standard recovery options.

TPCSRMXT

Customizes the TPCF device preferencing to address site-specific needs not completely served by the CA MIA standard preferencing options.

More information:

User Exits

Dynamic Detection and Notification (DDN)

Diagnosing delays in tape device allocation is challenging, especially when multiple systems are involved. The Delay Detection and Notification (DDN) feature simplifies tape device allocation delay detection and provides real-time diagnostics to z/OS system operators when a problem occurs. This information allows operators to expedite resolution of tape device allocation delays involving CA MIA managed devices.

Example:

To enable DDN detection,issue the following command:

MIM SETOPTION DDN=ON

Contention Delay Detection

When DDN contention detection is turned on, users can be automatically notified of potential tape device delays due to a task owning tape device allocation locks for an extended period of time.

To enable contention delay warnings to be issued on a reoccurring five-minute interval, issue the following command:

MIM SETOPTION DDN(ON, CONTENTION=5)

For more information, see the DDN option in the CA MIM Statements and Commands Reference Guide.

Notes:

• Place the DDN SETOPTION in your MIACMNDS member to enable the feature during CA MIA initialization. The default is OFF and has a range of 1 to 60 minutes.
• If DDN is turned off, then no allocation delay analysis is performed.
• To diagnose an issue presented by DDN further, use the ANALYZE TAPEDELAY command.

WAIT/NOHOLD Detection

When the CA MIM DDN Wait/NoHold detection feature is turned on, a warning is issued when two or more tasks monopolize a set of device allocation locks due to excessive Wait/NoHold responses.

To enable DDN Wait/NoHold detection to report a loop exceeding 10 iterations, issue the following command:

MIM SETOPTION DDN(WAITNOHOLD=10)

For more information, see the DDN option in the CA MIM Statements and Commands Reference Guide.

Notes:

• To enable the feature during CA MIA initialization, place the DDN SETOPTION in your MIACMNDS member. The default is OFF and has a range of 10 to 9999 responses.
• DDN recognizes when work is progressing on the system and only DDN notifies operators when a tape device monopolization condition persists.
• If DDN is turned off, then no allocation delay analysis is performed.
• To diagnose an issue presented by DDN further, use the ANALYZE TAPEDELAY command.