>Richard,
>
>We installed our 3494/3590E1A in june 1999. Since then we noticed several
>read only tapes every week. We tried new micro code without success. Then we
>reduced the cleaning cycle from every 500 mounts to 250 mounts. No more read
>only tapes came up since then.
>
>Seems that at least our drives don't request cleaning. Or must they be
>configured to do so?

Hi, Reinhold -

From manuals and experience, I have seen no way that cleaning requests can be
suppressed on 3590 drives.  When they need cleaning they will say so on their
front panel and send notification to both the 3494 Library Manager (via the
RS-422 interface) and the host operating system (via SCSI/FC).  They show up
in AIX as Error Log entries of ERRID_TAPE_ERR6 (/usr/include/sys/errids.h).
The 3494 will respond by adding the request to its Clean Queue, which it will
process when the drive is free.  (Note that unusually long TSM tape mount
times can be due to the drive busy undergoing a cleaning.  You can see when
drives underwent cleaning in the LM's Transaction Log: search on "CLEAN" or
"CQ".  Count of cleans per drive can be seen on the drive's panel, under the
Show Statistics menu, Clean Mounts.)

I concur with you that regular drive cleaning will help prevent tape I/O
errors.  I think the manual "IBM Magstar Tape Products Family: A Practical
Guide" recommends against it so as to both minimize wear on the drive and to
prevent drive availability being jeopardized because it is undergoing a
scheduled cleaning.  Computer rooms are by no means "clean rooms", and so
scheduled cleaning is certainly justified in many environments.

   Richard