Are you sure it is not something like a restore is running and a
     migration kicks off and waits for the restore to finish but it is a
     lengthy restore thus the migration times out and cancels the
     request... ? If you can view a history of mounts in the library I
     would do so to really see if the drives are all full and what might =
be
     using them...
     Also if you have migrations running and all the tape drives full =
AND
     someone needs a restore from tape it will kill the migration for a
     higher priority restore...
     later
          Dwight