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Date:      Wed, 28 Apr 1999 14:26:24 -0400 (EDT)
From:      "Christopher T. Johnson" <cjohnson@neunacht.netgsi.com>
To:        dillon@apollo.backplane.com (Matthew Dillon)
Cc:        shocking@prth.pgs.com, current@FreeBSD.ORG
Subject:   Re: Further on tape & CAM problems
Message-ID:  <199904281826.OAA37667@neunacht.netgsi.com>
In-Reply-To: <199904281806.LAA07782@apollo.backplane.com> from Matthew Dillon at "Apr 28, 99 11:06:09 am"

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Matthew,
Thanks  I should have been more clear.

The amber LED on 8205s and 8505s and any of the half hight drives blink when
they need cleaning.  This is the original 8200 full hight drives.  They
have no cleaning indicator.

The drive is cleaned every monday before the amflush.  We use exabyte 8mm
cleaning cartridges as specified for the 8200.  When the problem first
occured I immedieatly used the cleaning cart and that did not solve the
problem of the amber light.

REGARDLESS!
	The drive is reporting an error condition and that error is NOT
	getting back to user land.  I've verified the problem with amdump
	amflush and dd.  In ALL cases once the amber light goes on solid
	systat -vmstat shows a solid 1.4MB/second data transfer into
	never never land.

	Thanks,
		Chris

P.S.  This is not the only reply suggesting head cleaning.  I should have
mentiond that.  I did mention that I replaced the drive rather than 
suspect our drivers.  *GRIN*


>     The amber LED on exabytes typically means 'drive needs cleaning'.  Exabyte
>     drives should be cleaned once or twice a week depending on how heavily
>     you use them.  If an exabyte drive is not cleaned on a regular basis, the
>     transfer rate will drop steadily as the drive is forced to rewrite sectors
>     on the tape.  Additionally, the larger gaps produced by the rewrites will
>     result in much less storage per tape.
> 
>     I dunno about the 8200.  The mamoth exabytes can do 3 MBytes/sec.  Any
>     exabyte drive should transfer up to its rating.  If it transfers more
>     slowly, it is either damaged or in need of cleaning.
> 
>     When purchasing cleaning tapes, be sure to purchase the correct cleaning
>     tapes for the type of drive you have.  Exabytes tend to be fairly sensitive
>     and putting in the wrong sort of cleaning tape can damage the head.
> 
> 					-Matt
> 					Matthew Dillon 
> 					<dillon@backplane.com>
> 
> :Some extra information on tape problems:
> :
> :FreeBSD neunacht.netgsi.com 4.0-CURRENT FreeBSD 4.0-CURRENT #0: Thu Apr 22
> :16:50:33 EDT 1999 root@:/m/src/sys/compile/NEUNACHT i386
> :
> :This is SMP machine with scsi only.
> :
> :The tape drive is an EXABYTE-8200.
> :
> :When doing tape IO that lasts for an extend period of time the tape drive
> :will show an amber light.  This normally means SCSI activity.  At that
> :point any reads or writes to the device happen at 1.4Mbytes/second when
> :the max I know that this drive will do is 0.24 Mbytes/second.
> :
> :We've replaced the tape drive.  We've tested with different tapes.
> :
> :It LOOKS like the drive is detecting some sort of error and then going
> :into "toss data mode".  This has cost me lots and lots of backups and
> :is very distressing.
> :
> :One interesting data point.  When I issue an mt erase command it runs for
> :a fairly long time.  It should runn for just over 2 hours.  It gets about
> :3/4s of the way and stops.  Again with the orange light.  The interesting
> :data point is that four tapes have all stopped at almost the same point.
> :(Visual inspection of amount of media left on the reels.)
> :
> :Any help would be very nice.
> :
> :	Thank you,
> :		Chris
> 



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