ARC1321I

Explanation
 If this message has been issued as the result
of a request to backup an uncataloged data set, the request is missing
the required UNIT parameter or the UNIT parameter has been specified
with an unsupported device type.
 If this message is issued
as the result of a request to back up a cataloged data set, the data
set has been cataloged to an unsupported device type.
 See z/OS Migration,
for a list of supported devices.

System action
 The backup operation ends. DFSMShsm processing continues.

Programmer response
 If the data set is uncataloged, correct
the invalid UNIT parameter and retry the operation. If the data set
is cataloged, notify the storage administrator.

Source
 DFSMShsm