IEF503I

Explanation
During allocation processing, an error occurred
when the system read a volume label. The error can be one of the following:
An uncorrectable I/O error occurred.
An unlabeled tape was mounted before it had been requested.
A non-standard label tape was mounted. The user non-standard label
handling routine rejected the label or the installation had provided
no user non-standard label handling routine.
The system detected a volume serial number that was not valid
on a direct access storage device (DASD).

In the message text: dev
The device number for the unit.

System action
The system unloads the volume and issues message
IEF234E.

Operator response
Do one of the following:
If an uncorrectable I/O error or an incorrect volume serial number
was the problem, and the message recurs for the same volume, ensure
that the label is correct.
If an unlabeled volume had been mounted before it was requested,
this is the problem. Do not remount the volume until it is requested.
If a non-standard label volume was being used, notify the system
programmer.

System programmer response
If the volume should use a non-standard
label, ensure that a non-standard label handling routine exists. 
Otherwise, provide a standard label for the volume.
If the system
issued this message for a DASD, ensure that the device is functioning
correctly.  Verify that the device has a correct standard label. 
If necessary: Refresh the volume label and try to vary the device online so
that the system can attempt to verify the volume serial number.
If the device is mountable, you also can replace the volume with
one having a standard label.

Try to vary the device online so that the system can attempt
to verify the volume serial.  Further errors can indicate that the
device experienced a hardware failure; in this case, contact hardware
support.

Source
Allocation

Module
IEFAB473

Routing code
*/3/4

Descriptor code
4/5