What is REORGadon?

REORGadon (HSM/R) is a tool for reorganizing IBM’s Hierarchical Storage Manager (DFSMShsm) control data sets (CDS) and small data set packing data sets (SDSP).

REORGadon provides HSM control data set or SDSP reorganization while the files are active and online to HSM, and without having to shutdown and restart HSM.

Why is REORGadon Necessary for a CDS?

HSM CDSs are VSAM key sequence data sets (KSDS). These CDSs contain records that describe data set entries that have been processed by HSM. As records are added to a KSDS, VSAM eventually takes CI and CA splits. The CI and CA splits fragment space within the KSDS eventually resulting in an out of space condition. HSM warns of impeding out of space conditions thru issuance of the ARC0909E and ARC0911E error messages. These messages indicate that the current threshold for space has been exceeded. This threshold can be changed via the SETSYS MONITOR command.

Further information about the CDSs can be obtained via the QUERY command with CONTROLDATASETS parameter. Status is reported in the ARC0148I and ARC0948I messages.

Without REORGadon, IBM documents:

  • If the MCDS, BCDS, or OCDS is full enough to require action, DFSMShsm should be shut down.

IBM goes on to suggest:

  • Prior to a DFSMShsm shutdown, there are some options you can use:
    • Delete old or unneeded records, such as old statistics records, by using the DELETE parameter of the FIXCDS or REPORT command.
    • Run migration cleanup using the SETSYS command with the SECONDARYSPMGMTSTART parameter and the DEFINE command with the SECONDARYSPMGMTCYCLE parameter.
  • After DFSMShsm shutdown:
    • Reclaim fragmented space by performing an IDCAMS EXPORT and IMPORT of the data set or by copying the data set out and back using the IDCAMS REPRO command. If reclaiming fragmented space does not provide sufficient space, a larger control data set should be allocated.