If the backup device is unavailable, or for another appropriate reason,
you choose not to let a user or users access a backup device, you should
deny media requests when they appear. To deny a media request, use the
REPLY command to assign the LDEV number 0 to the user's PIN. So,
for example, to deny a media request you received from the user with PIN
23, enter:
The user receives a message reporting that the device (the media drive) is
unavailable. You may want to send the user another message using TELL
explaining the situation in detail and estimating when the device might be
available.