Event-driven migration example scenario

In the following event-driven migration example scenario, there are three DFSMShsm hosts which manage three storage groups. A portion of the ARCCMDxx parmlib member of SYS1.PARMLIB is shown for each host. The basic storage group definitions are shown for each storage group.

DFSMShsm host 1:

  ⋮
    /* Start secondary space management at 12:30 AM. */
    SETSYS SECONDARYSPMGMTSTART(0030 0200)
    DEFINE SECONDARYSPMGMTCYCLE(YNNNYNN -
      CYCLESTARTDATE(2011/09/12))
  ⋮
    /* Do not perform event-driven migration. */
    SETSYS NOINTERVALMIGRATION
    SETSYS ONDEMANDMIGRATION(N)
  ⋮

DFSMShsm host 2:

  ⋮
    /* Start primary space management at 2 AM. */
    SETSYS PRIMARYSPMGMTSTART(0200 0400)
    DEFINE PRIMARYSPMGMTCYCLE(Y -
      CYCLESTARTDATE(2011/09/12))
  ⋮
    /* Perform event-driven migration (on-demand). */
    SETSYS NOINTERVALMIGRATION /* Ignored when SETSYS ODM(Y) is specified. */
    SETSYS ONDEMANDMIGRATION(Y)
  ⋮

DFSMShsm host 3:

  ⋮
    /* Perform event-driven migration (on-demand). */
    SETSYS NOINTERVALMIGRATION  /* Ignored when SETSYS ODM(Y) is specified. */
    SETSYS ONDEMANDMIGRATION(Y)
  ⋮

The storage groups are defined:

         NAME ===> SG1
         MIGRATE SYSTEM/SYSPLEX NAME ===>
         AUTO MIGRATE ===> Y
         MIGRATION AND ALLOCATION THRESHOLDS: HIGH ===> 85  LOW ===> 70
  ⋮
         NAME ===> SG2
         MIGRATE SYSTEM/SYSPLEX NAME ===>
         AUTO MIGRATE ===> Y
         MIGRATION AND ALLOCATION THRESHOLDS: HIGH ===> 95  LOW ===> 80
  ⋮
         NAME ===> SG3
         MIGRATE SYSTEM/SYSPLEX NAME ===>
         AUTO MIGRATE ===> N
         MIGRATION AND ALLOCATION THRESHOLDS: HIGH ===> 20  LOW ===> 0

Immediately after SMS issues an ENF72 event code signaling a volume in storage group SG1 or SG2 has exceeded the high threshold (85% for SG1 and 95% for SG2), DFSMShsm host 2 and DFSMShsm host 3 perform on-demand migration (immediate space management) on eligible volumes that belong to SG1 and SG2. DFSMShsm host 2 and DFSMShsm host 3 perform on-demand migration on eligible volumes in these storage groups because the SETSYS ONDEMANDMIGRATION(Y) setting is specified and the storage groups are defined with AM=Y (Auto Migrate, yes). On-demand migration is performed on SG1 and SG2 as needed throughout the day on both hosts, except when primary space management is running between 2:00 AM and 4:00 AM on DFSMShsm host 2. During this time, DFSMShsm host 3 is available to perform on-demand migration and on-demand migration is paused on DFSMShsm host 2. After primary space management completes, DFSMShsm host 2 is available to perform on-demand migration again.

DFSMShsm host 1 is reserved for handling high priority DFSMShsm requests. The only space management task DFSMShsm host 1 performs is secondary space management between 12:30 AM and 2:00 AM. DFSMShsm host 1 does not perform interval migration because the SETSYS NOINTERVALMIGRATION setting is specified. Additionally, DFSMShsm host 1 does not perform on-demand migration because the SETSYS ONDEMANDMIGRATION(N) setting is specified.

None of the DFSMShsm hosts perform event-driven migration on volumes that belong to storage group SG3 because it is defined with AM=N (Auto Migrate, no).

All eligible volumes are processed by event-driven migration until the low threshold is reached or until there are no eligible data sets to migrate.

Event-driven migration example scenario

Related reading