We are having a similar problem, with LTO4's in a Scalar500 - scratch tapes 
were failing to complete any mounting process then going into a Private status 
'to prevent re-access' as per ANR8778W.

The problems started when we had two devclasses for LTO, one with 
DRIVEncryption set to ON (LTO_ENCRYPT), and the other NO (LTO). Since changing 
the LTO devclass to Allow, checking the tapes out and labelling then in again 
with a checkin of 'Scratch' seems to alleviated the ongoing status change. We 
are still getting the i/o errors on the volumes reporting KEY=7 (write protect) 
but the usual 'i/o error reading label', '<vol> could not be mounted' and 
'scratch vol changed to Private to prevent re-access' have gone.

Have you been fiddling with Drive Encrypted device classes?

------
Matthew Large
TSM Consultant

-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of 
John C Dury
Sent: 02 April 2008 22:57
To: ADSM-L AT VM.MARIST DOT EDU
Subject: [ADSM-L] multiple tapes being detected as WRITE PROTECTED in SL500 
library

We have an SL500 tape library with 50 tapes in it and 4 IBM Ultrium LTO4
drives. One of the drives consistently is detecting tapes that get mounted
to it as WRITE PROTECTED. We have replaced the fiber between the drive and
the DS-4900 SAN switch and also moved it into a new port in the SAN switch
in case the GBIC was causing the problem.
This all started with the same drive getting multiple MEDIA FAULT errors on
the same LTO4 drive and marking tapes as READ ONLY. Sun/STK has since
replaced the same drive and now the drive in the same slot on the SL500 is
getting the WRITE PROTECTED errors on the tapes that are mounted in it.

Could it be the new drive has a bad sensor in it? I'm just not sure what
else we can replace at this point to fix this. And if that is the case, are
these drives (IBM Ultrium) really that unreliable and get errors this
often? Or could it be something with the SL500? This is a new tape library
with new drives that is only a few months old. This is our production
system and having it mark 10-12 tapes a night as unavailable is quite a
pain when we only have 50 tapes in the whole library.
Thanks,
John
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