DFSMSrmm ACS Support
Note: This is publication is now archived. For reference only.
Published 06 November 2003
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Authors: Mary Lovelace
Starting with DFSMSrmm V2.10, you can use your SMS ACS routines to assign a VRS management class and to select a specific scratch pool. To enable this function, you update your SMS environment to allow a management class to be used in place of the VRS management value assigned in the EDGUX100 user exit, and a storage group name to be used as a scratch pool name.
With DFSMSrmm V2R10 or higher, you can use your SMS ACS routines to select a specific scratch pool and storage group to be assigned to create new data on tape, and set a management class to retain and move a data set on tape. You move your policy and scratch pool decisions to your SMS ACS routines. For non-system managed tapes, DFSMSrmm calls the ACS routines to allow a management class and storage group assignment. For SMS managed tapes, SMS calls the ACS routines directly.
To enable DFSMSrmm ACS support, you must have the SMS subsystem active and have a valid SMS configuration.
With OS/390 V2R10 or higher, SMS ACS routines are always called by DFSMSrmm if you have a tape mount outside a SMS managed tape library.
ACS processing for non-system managed tapes can be tailored by the PARMLIB member EDGRMMxx OPTION subparameters PREACS and SMSACS. In the following sections are the operands of the EDGRMMxx OPTION subparameters.
Specify the PREACS operand to control whether DFSMSrmm-supplied values and EDGUX100 installation exit-supplied values are input to SMS pre-ACS processing:
- NO Specify NO to avoid DFSMSrmm pre-ACS processing using the DFSMSrmm EDGUX100 installation exit.
- YES Specify YES to enable DFSMSrmm pre-ACS processing using the DFSMSrmm EDGUX100 installation exit.
The scratch pooling and policy assignment rules are per default coded in EDGUX100 user exit. You can move your decisions to the SMS ACS routines, where you can use ACS input variables as a base for management class and storage group assignment:
- NO Specify NO to prevent DFSMSrmm from calling the SMS ACS processing to obtain management class and storage group names. DFSMSrmm system-based scratch pooling, and scratch pooling and VRS management values based on the EDGUX100 installation exit are used.
- YES Specify YES to enable DFSMSrmm calls to the SMS ACS processing to obtain management class and storage group names. If values are returned by the SMS ACS routines, the values are used instead of the DFSMSrmm and EDGUX100 decisions.
We recommend that you move pooling decisions and VRS management value assignment out of the EDGUX100 user exit. We also recommend that you do not implement PREACS processing, and do not use the EDGUX100 user exit except for the following reasons:
- Cartridge loader control (ACL)
- Data set recording
- Sticky label customization
- Request ignore of volumes
How it works
Use ACS routines for scratch pooling based on tape storage group names. Using ACS processing to set a storage group name overrides all other pool selection methods. DFSMSrmm provides support for non-system-managed tape and for system-managed manual tape libraries. This support enables pooling at the individual volume level. You assign a storage group name to each volume by using DFSMSrmm TSO subcommands or by using pooling information that you define with the DFSMSrmm EDGRMMxx PARMLIB VLPOOL command. DFSMSrmm calls ACS routines passing environment information, including the pool identified by DFSMSrmm system-based pooling. The ACS routine can optionally set a storage group name, which overrides the DFSMSrmm system-based pool.
ACS support for non-system managed volumes
In a non-system-managed library, DFSMSrmm supports SMS ACS routines in different ways:
- DFSMSrmm will directly call the ACS routines if you have specified SMSACS(YES) in the EDGRMMxx PARMLIB member to allow a management class and storage group to be assigned.
Use ACS routines for scratch pooling based on tape storage group names. Using ACS processing to set a storage group name overrides all other pool selection methods. DFSMSrmm provides support for non-system-managed tape and for system-managed manual tape libraries. This support enables pooling at the individual volume level. You assign a storage group name to each volume by using DFSMSrmm TSO subcommands, or by using pooling information, which you define with the DFSMSrmm EDGRMMxx PARMLIB VLPOOL command. DFSMSrmm calls ACS routines passing environment information, including the pool identified by DFSMSrmm system-based pooling. The ACS routines can optionally set a storage group name, which overrides the DFSMSrmm system-based pool.
- You can use the EDGUX100 user exit to call SMS ACS routines to assign a VRS management class value and a scratch pool if you have specified PREACS(YES).
- DFSMSrmm uses the VLPOOL definitions to select a default DFSMSrmm pool using DFSMSrmm system-based pooling. DFSMSrmm sets a pool prefix if a specific pool is selected.
- DFSMSrmm calls the EDGUX100 installation exit to obtain a pool prefix value. If a pool prefix value is returned, the pool prefix value returned by the EDGUX100 installation exit overrides the DFSMSrmm selected pool.
- DFSMSrmm returns the selected value in the MSPOOL read-only variable if the MSPOOL variable is not already set by the pre-ACS exit.
- You can use both the DFSMSrmm direct call and the user exit EDGUX100 call together to make the decision.
- Use pre-ACS processing to obtain the DFSMSrmm system-based pool or the EDGUX100 installation exit pool prefix as an input value to the ACS routines in the MSPOOL read-only variable. During pre-ACS processing, DFSMSrmm does not make the RMMPOOL environment call to the ACS routine. During pre-ACS processing for new allocations:
If you are using PREACS processing, and you have installed the EDGUX100 user exit, DFSMSrmm processes the functions in the following sequence:
- ACS processing calls PRE-ACS exit.
- DFSMSrmm calls EDGUX100 and sets MSPOOL and MSPOLICY.
- ACS decides whether the entity is system managed or not. During processing the four PRE-ACS read-only variables can be used as input to the decision.
- For non-system managed tape we enter DFSMSrmm ACS support. ACS processing is called for storage group processing, and again for management class processing.
- DFSMSrmm calls EDGUX100 for its basic exit function.
Non-system-managed tape libraries
A non-system-managed tape library is all the volumes, shelves, and drives that are not in an automated tape library dataserver or manual tape library. You might know this as the traditional tape library in a data center or as an automated environment that is not system-managed. DFSMSrmm provides complete tape management functions for the volumes and shelves in this traditional tape library.
All tape media and drives supported by z/OS are supported in this environment. Use DFSMSrmm to fully manage all types of tapes in a non-system-managed tape library, including 3420 reels, 3480, 3490, 3590, and 3592 cartridge system tapes.
You can also use DFSMSrmm to manage volumes in any automated tape library that has special software including an IBM Tape Library Data server that is managed using Basic Tape Library Support (BTLS).
Most non-IBM libraries do not provide support for system-managed tape, so we consider them to be the traditional tape libraries.
The IBM direction is to replace DFSMSrmm exit function with an alternative, either SMS policy or PARMLIB option.
This material has not been submitted to any formal IBM test and is published AS IS. It has not been the subject of rigorous review. IBM assumes no responsibility for its accuracy or completeness. The use of this information or the implementation of any of these techniques is a client responsibility and depends upon the client's ability to evaluate and integrate them into the client's operational environment.
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