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 the ACS routines have assigned it to a storage class that does not have the GUARANTEED SPACE attribute or does not assign it to any storage class. The ACS routine is then changed to assign the data set to a storage class with the GUARANTEED SPACE attribute. Also, the original storage class is changed to include the GUARANTEED SPACE attribute. Therefore, the recall 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 recalled, you must perform one of the following actions:

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 migrated. The volumes may need to be converted to SMS management first. It may 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 is applicable only if the volumes are already SMS-managed.
Use the RECALL command with the FORCENONSMS and the VOLUME parameters. This RECALL command causes the data set to be recalled 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 migrated, it is recalled to a single volume.