z/OS DFSMShsm Managing Your Own Data
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How does DFSMShsm manage space?

z/OS DFSMShsm Managing Your Own Data
SC23-6870-00

DFSMShsm manages space by:
  • Freeing overallocated space
  • Deleting expired data sets
  • Moving eligible data sets that you have not used recently from a DFSMShsm-managed volume to a migration level 1 or migration level 2 volume

DFSMShsm can also move data sets from migration level 1 volumes to migration level 2 volumes or directly from level 0 to migration level 2 volumes. When you refer to a migrated data set, DFSMShsm automatically recalls it to a level 0 volume so you can use it.

DFSMShsm can migrate or delete data sets on volumes either automatically or by command. If you do not want to wait for automatic space management to run, you can use the DFSMShsm user command HMIGRATE to migrate one or more of your data sets. You can also use the DFSMShsm user command HDELETE to delete one or more of your migrated data sets.

DFSMShsm uses the following functions to manage space:
  • Space Management
    • Automatic volume space management
      • Primary
      • Interval migration
      • On-demand migration
    • Automatic secondary space management
  • Recall
    • Automatic recall
    • Command recall

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