TAPERECALLLIMITS: Specifying limits to continuously mounted ML2 tapes during multiple recalls

Explanation: TAPERECALLLIMITS(TASK(time) TAPE(time)) is an optional parameter specifying the total time that a recall task can utilize a single tape mount for processing recall requests before criteria is used to possibly demount the tape. This parameter does not apply to tape devices prior to 3480 tape devices.

Suparameter	Explanation
TASK(time)	Allows you to specify the number of minutes that a DFSMShsm recall task can process recall requests from a single tape mount before DFSMShsm decides whether to demount the tape or to continue processing. Once that time is exhausted, each time the recall task completes the processing of its current recall request, DFSMShsm decides whether to demount the tape or to continue processing. If the maximum number of tape recall tasks within the host are running and a higher priority tape recall request exists that can be attempted immediately, then the task is freed up to process other requests.
TAPE(time)	Allows you to specify the number of minutes that a recall task can process recalls from a single tape mount before additional criteria are considered. Once this time is exhausted, the recall task completes processing of its current recall request and then DFSMShsm determines whether to demount the tape or to continue processing. If another DFSMShsm host requires the mounted tape for a higher priority recall, then the tape is demounted. This results in a tape take-away from recall.

Suparameter

Explanation

TASK(time)

Allows you to specify the number of minutes that a DFSMShsm recall task can process recall requests from a single tape mount before DFSMShsm decides whether to demount the tape or to continue processing. Once that time is exhausted, each time the recall task completes the processing of its current recall request, DFSMShsm decides whether to demount the tape or to continue processing. If the maximum number of tape recall tasks within the host are running and a higher priority tape recall request exists that can be attempted immediately, then the task is freed up to process other requests.

TAPE(time)

Allows you to specify the number of minutes that a recall task can process recalls from a single tape mount before additional criteria are considered. Once this time is exhausted, the recall task completes processing of its current recall request and then DFSMShsm determines whether to demount the tape or to continue processing. If another DFSMShsm host requires the mounted tape for a higher priority recall, then the tape is demounted. This results in a tape take-away from recall.

Once the recall processing stops for a specific recall task on a DFSMShsm host, then all queued recall requests on that host that require the demounted tape volume are excluded from consideration for five minutes. This allows other hosts an opportunity to retry their delayed requests for the demounted tape volume.

When DFSMShsm processes multiple recall requests that utilize one tape mount, the recall task processes the highest priority tape recall request which requires the currently mounted tape. If DFSMShsm does force a demount of the tape volume, then the task and the tape are freed up to process other higher priority recalls.

SMS relationship: Parameter has the same meaning when applied to SMS-managed or non-SMS-managed DASD volumes or data sets.

SETSYS default: None.

DFSMShsm default: If you do not specify either of the TAPERECALLLIMITS subparameters, then the default time used is 15 minutes for TASK and 20 minutes for TAPE.

Note:

TAPE(time) is longer than TASK(time) because TAPE(time) requires delaying additional queued requests.
The Storage Administrator is able to disable the TAPERECALLLIMIT function by setting both the TASK and the TAPE time to large values, such as 1000 or even 65535 minutes.