MEDIA_UNMOUNT_DELAY is exactly what you want to tune. I ran into the very same 
thing. What was happening in my environment was that NBU was issuing a SCSI 
drive unmount command, before the tape was finished unwinding. Setting 
MEDIA_UNMOUNT_DELAY=1800 did the trick. My drives no longer are being downed as 
a result of this condition.

--Steve

On Mon, 2 Jun 2003, Paul Gimpelev wrote:

> Date: Mon, 2 Jun 2003 17:39:50 -0400
> From: Paul Gimpelev <paulg AT CDCNA DOT COM>
> To: veritas-bu AT mailman.eng.auburn DOT edu
> Subject: [Veritas-bu] Tape unmount delay
> 
>       Does anyone know if NBU 4.5 has a tunable "tape unmount delay"?  I
> don't mean the MEDIA_UNMOUNT_DELAY that they use to determine how long the 
> tape
> stays in the drive post backup/restore.  I am running into an issue where it 
> is
> possible that NBU does not wait long enough for a DLT IV drive to rewind and
> initiates an attempt for a robotic tape move prematurely.  This in turn causes
> the drive to go down.
> 
> I would appreciate any information from someone who had a similar occurence.
> 
> Thanks,
> 
> paulg
> _______________________________________________
> Veritas-bu maillist  -  Veritas-bu AT mailman.eng.auburn DOT edu
> http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu
> 

-- 
========================================

Steven L. Sesar
Senior Operating Systems Programmer/Analyst
UNIX Applications Services R10A
The MITRE Corporation
202 Burlington Road - MS K101
Bedford, MA 01730
tel: (781) 271-7702
fax: (781) 271-2600
mobile: (617) 893-9635
email: ssesar AT mitre DOT org

========================================