Date: Wed, 28 Apr 1999 11:06:09 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: "Christopher T. Johnson" <cjohnson@neunacht.netgsi.com> Cc: shocking@prth.pgs.com (Stephen Hocking-Senior Programmer PGS Tensor Perth), current@FreeBSD.ORG Subject: Re: Further on tape & CAM problems Message-ID: <199904281806.LAA07782@apollo.backplane.com> References: <199904281654.MAA37459@neunacht.netgsi.com>
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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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