Specifying pools in systems running under JES3

Because DFSMShsm returns a list of volumes to JES3 at converter/interpreter time, the system pools that are running under JES3 have restrictions on when they can be established. You can specify pool configurations and recall options only at designated times. You must specify the pool configuration command in the ARCCMDxx member that is used when you start DFSMShsm with HOSTMODE=MAIN. (A pool configuration that is specified when you are starting HOSTMODE=AUX is ignored.) You cannot change pool configurations until the MAIN DFSMShsm restarts. Pool configurations and recall options must be consistent in all z/OS® images that run DFSMShsm with the appropriate HOSTMODE and perform the JES3 locate function.

The ADDVOL, DEFINE, DELVOL, and SETSYS commands determine the configuration of pools of volumes. When DFSMShsm is used with JES3, the DFSMShsm general pool and user-defined pools can be configured only as a result of the commands in the ARCCMDxx member processed when DFSMShsm is being initiated. Certain variations of these DFSMShsm commands are accepted only during that initialization period. The one exception is the DELVOL command. The DELVOL command is accepted at any time after initialization by any DFSMShsm that is running in the JES3 image. Therefore, JES3 does not expect a data set on a volume that is unusable. For example, you could use the DELVOL command to delete a primary volume that has I/O errors, so that DFSMShsm does not tell JES3 to use that volume.

To ensure that pools function correctly in a system running under JES3, consider the following conditions:

  1. Before you can define pools in each z/OS image, you must specify the following commands for each DFSMShsm host that you are starting in that image:
    • A SETSYS JES3 command. The JES3 parameter of the SETSYS command determines the need for the general pool. For a JES3 system, DFSMShsm builds the general pool when you start HOSTMODE=MAIN. Because information from the ADDVOL command is used to build the general pool, DFSMShsm must know that JES3 is the job entry system before the first ADDVOL command is issued for a primary volume. Once the job entry subsystem is determined, you cannot change it until DFSMShsm is restarted.
    • A SETSYS RECALL command with its appropriate subparameter. The ANYSTORAGEVOLUME and PRIVATEVOLUME subparameters of the RECALL parameter of the SETSYS command are not accepted after the initialization period of DFSMShsm has passed, because the method of recalling data sets determines the volumes that qualify for the general pool.
    • An ADDVOL command for primary volumes that DFSMShsm is to manage.You must specify the PRIMARY parameter of the ADDVOL command for a volume before that volume is included in any pool. Subsequent ADDVOL commands for the same DFSMShsm primary volume must not change the information used by DFSMShsm to define pools. The volume must still:
      • Be online (see the note in item 2)
      • Be permanently resident or reserved
      • Have the same automatic recall parameters specified

      The ADDVOL command can be issued at any time for volumes other than DFSMShsm primary volumes just as in a DFSMShsm environment without JES3.

    Note: Be sure that you include the ADDVOL command specifications in the ARCCMDxx member of SYS1.PARMLIB so that DFSMShsm recognizes the volumes at each startup. If ADDVOL commands for ML1 volumes are not in the ARCCMDxx member, DFSMShsm does not recognize that they are available unless you issue an ADDVOL command at the terminal for each ML1 volume.
  2. The POOL parameter of the DEFINE command can be issued only during initialization of DFSMShsm. DFSMShsm does not accept more than one DEFINE command for the same pool ID during initialization. All DEFINE commands issued for volumes to be included in a data set pool must be preceded by an ADDVOL command for each volume.
    Note: For data set pooling, volumes that are offline at DFSMShsm startup time are added to DFSMShsm as offline and are not added to the data set pool. When these volumes become available, DFSMShsm must be restarted to add the volumes as online and include them in the data set pool.
  3. The VOLUMEPOOL parameter of the DEFINE command can be issued only during initialization of DFSMShsm. DFSMShsm will not accept more than one DEFINE command for the same pool ID during initialization. At least one volume in the volume pool must have been added with a previous ADDVOL command to the list of volumes DFSMShsm manages or owns.
  4. You can specify other parameters of the DEFINE command as if in a DFSMShsm environment without JES3.
  5. Be sure that you define the same data set and volume pools in all z/OS images that can process the volumes.
  6. To ensure that recall is to a volume that you choose, do not refer to any data set eligible for space management before the appropriate pool configuration in that z/OS image has been defined to DFSMShsm.
  7. Specify each DFSMShsm primary volume with the same parameters (for a given volume) in each z/OS image. The mount status of permanently resident or reserved prevents DFSMShsm primary volumes from being demounted. One of these attributes must be in effect for each DFSMShsm primary volume.
  8. When a local z/OS image assumes the function of the global image, any required DFSMShsm functions that are performed by the previous global image must be active on the new global image. Specify the same pool configuration on each image to protect this type of JES3 activity.
  9. Each JES3 z/OS image can have unique user-defined pools. However, if your system uses unique user-defined pools whose volumes are not accessible to the global z/OS image, you must use job classes or JES3 JCL to direct all jobs that access the unique user-defined pools to the z/OS image that can access them. This is a requirement when both the global and the local z/OS images request JES3 locates. If any z/OS image has access to a primary volume in a data set pool, it must have access to all primary volumes in that data set pool, or the job could fail. If you decide not to give all JES3 z/OS images access to all primary volumes, use caution when you define and operate with unique data set pool configurations.
  10. If any device containing a volume in a data set pool is designated as a device managed by JES3, all other volumes in that data set pool must reside on JES3-managed devices. JES3 schedules jobs only on z/OS images that have access to all volumes that the jobs require.
  11. Any z/OS image that runs the job must have access to all the volumes passed to JES3 by DFSMShsm.
Parent topic: Pools in systems running under JES3