When it's a "known limitation", according to TSM support.

We have a problem with our TSM server occasionally deciding that an
ACSLS tape is "unavailable", requiring a TSM restart before the tape
can be used.  In my opinion, any problem (excuse me, "known
limitation") where a function stops working until the server is
restarted is a bug.  TSM support disagrees, as indicated in their
response to my PMR:

  My apologies if I gave you the wrong impression that this code is
  broke.  As mention above this is a known limitation with in the code.
  Since this is a limitation and the code is not broken I cannot open
  an APAR against it.
  .
  My recommendation is to open a DCR with marketing on this issue and
  they will be able to track that for you.

I still think a "limitation" that prevents normal operation of the
server is a bug.
--


Matt Simpson --  OS/390 Support
219 McVey Hall  -- (859) 257-2900 x300
University Of Kentucky, Lexington, KY 40506
<mailto:matt AT uky DOT edu>
mainframe --   An obsolete device still used by thousands of obsolete
companies serving billions of obsolete customers and making huge obsolete
profits for their obsolete shareholders.  And this year's run twice as fast
as last year's.