Changes in the storage-class-to-data-set mapping

Consider the consequence of making a specific volume request in a storage class mapping that has changed. Assume that a data set is defined and one of the following conditions occur:

• The ACS routines do not assign the data set to any storage class.
• The ACS routines assigns the data set to a storage class that does not have the GUARANTEED SPACE attribute.

Later, assume one of the following changes occur:

• The ACS routine is changed so that it assigns the data set to a storage class with the GUARANTEED SPACE attribute.
• The original storage class is changed to include the GUARANTEED SPACE attribute.

Now, when you recover this data set, the recovery might fail because the requested volumes are not in the storage groups that receive GUARANTEED SPACE requests.

If an SMS-managed data set’s original storage class is changed to specify the GUARANTEED SPACE attribute before the data set is recovered, you must do one of the following:

• Change the ACS storage class routine so that a storage class without GUARANTEED SPACE is assigned to the data set.
• Change the storage class of the data set to a storage class without GUARANTEED SPACE, without recalling the data set, by using the IDCAMS ALTER command.
• Change the volume configuration in the appropriate storage groups to contain the volumes from which the data set was backed up. The volumes might need to be converted to SMS management first. It can be difficult to determine all of the volumes involved. DFSMShsm does not save all of the original volume serial numbers, only that of the volume on which the base data component resided.
• Change the set of storage groups to which the GUARANTEED SPACE storage class maps to include one that already has the necessary volumes defined. This step applies only if the volumes are already SMS-managed.
• Use the RECOVER command with the FORCENONSMS and the VOLUME parameters. This RECOVER command causes the data set to be recovered to a non-SMS-managed volume as a non-SMS-managed data set. You can then move, copy, or convert the data set as necessary.
  Note: If the data set was multiple-volume when it was backed up, it is recovered to a single volume.