Veritas-bu

[Veritas-bu] Stopping ltid

2004-04-21 12:20:48
Subject: [Veritas-bu] Stopping ltid
From: Ed.Toner AT eu.nabgroup DOT com (Ed.Toner AT eu.nabgroup DOT com)
Date: Wed, 21 Apr 2004 17:20:48 +0100
No, our tape drives are StorageTek STK9840 drives but the problem itself is
probably not unique to these drives. The drives themselves have a button
marked ipl which is handy enough but power cycling does the same thing.

To reset the MIR record you only need to write anything to the tape and
then unmount it. bplabel, tar or even just a backup. When the tape unmounts
the MIR is updated correctly. The MIR is only accessible by the tape drive
not the host and is used for block level positioning. I'm not sure if LTO
has the same mechanism.

The bptm log we would see -
00:05:43.436 [18575] <2> io_ioctl: command (5)MTREW 1 from (bptm.c.6212) on 
drive index 2
00:05:43.438 [18575] <2> io_ioctl: command (1)MTFSF 1 from (bptm.c.6403) on 
drive index 2
00:05:43.438 [18575] <2> io_position_for_write: position media id 021113, copy 
1, current number images = 30
00:05:43.439 [18575] <2> io_position_for_write: locating to absolute block 
number 379394, copy 1

and then this process would do nothing until either timing out 6 hours later or 
us reset the drive.

The STK firmware helped in that it deals with corrupt MIR records better and 
doesn't hang the drive.

I managed to eliminate most of the errors by freezing out tapes as suspect and 
removing the ones that failed a second time after being reset.

Cheers
Ed





Dan Logcher <dlogcher AT MIT DOT EDU> on 21/04/2004 17:03:24

To:    Ed.Toner AT eu.nabgroup DOT com
cc:    Veritas-bu AT mailman.eng.auburn DOT edu
Subject:    Re: [Veritas-bu] Stopping ltid


Ed.Toner AT eu.nabgroup DOT com wrote:

> We fixed this with a firmware upgrade to the 9840 drives.


Are these LTO Gen II drives?


> What caused our hangup was a media error which left a tape with a corrupt
> header (MIR) so it would hang the entire drive next time.  It tries to
> position and then never completes.


That appears to by the same thing that happens to our backups.  The drives get
hung after a Media write error.


> Hitting the reset button on the drive normally unlocked things but we had
> to freeze the media until it's backups expired to stop it being written to.
> Once expired you could write to the start of the tape which resets the MIR
> and the tape is fine after that.

I don't recall seeing a reset button on the drive.  I have to power cycle the
drive, which unlocks the Fibre channel.

Do you bplabel the tape to reset the MIR???

--
Dan




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