From owner-freebsd-scsi  Fri May 30 04:15:03 1997
Return-Path: <owner-freebsd-scsi>
Received: (from root@localhost)
          by hub.freebsd.org (8.8.5/8.8.5) id EAA11305
          for freebsd-scsi-outgoing; Fri, 30 May 1997 04:15:03 -0700 (PDT)
Received: from Sisyphos.MI.Uni-Koeln.DE (Sisyphos.MI.Uni-Koeln.DE [134.95.212.10])
          by hub.freebsd.org (8.8.5/8.8.5) with SMTP id EAA11289;
          Fri, 30 May 1997 04:14:53 -0700 (PDT)
Received: from x14.mi.uni-koeln.de (annexr2-40.slip.Uni-Koeln.DE) by Sisyphos.MI.Uni-Koeln.DE with SMTP id AA13095
  (5.67b/IDA-1.5); Fri, 30 May 1997 13:14:45 +0200
Received: (from se@localhost) by x14.mi.uni-koeln.de (8.8.5/8.6.9) id NAA03457; Fri, 30 May 1997 13:14:45 +0200 (CEST)
X-Face: "<d]#=8pzx);RzeqSKI86OVa7=!0/(uRa.+B.9Z9\eNUn@UG?!`y7yt2dFNn%k4'.}](uE%
 yCO)$e&Y1%3EO~ifu6Q-#YUM&JZ't,}JkPnAz,8Dj33u%@GBi%[Y#LHz$]h7a<p4)-jKI7~sKjlP-^
 EvA[G;]v&0]W!EL%shs,{7x0|oqN4YVIs5,NI#,V{9"WF):5&RkOhyj*#-IAG}Tnu;YCF,d
Message-Id: <19970530131444.53612@x14.mi.uni-koeln.de>
Date: Fri, 30 May 1997 13:14:44 +0200
From: Stefan Esser <se@FreeBSD.ORG>
To: Robert Schien <robsch@robkaos.ruhr.de>
Cc: freebsd-scsi@FreeBSD.ORG, Stefan Esser <se@FreeBSD.ORG>
Subject: Re: How to turn off DAT compression
References: <m0wXO8g-00066yC@robkaos.ruhr.de>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
X-Mailer: Mutt 0.74
In-Reply-To: <m0wXO8g-00066yC@robkaos.ruhr.de>; from Robert Schien on Fri, May 30, 1997 at 11:38:26AM +0200
Sender: owner-freebsd-scsi@FreeBSD.ORG
X-Loop: FreeBSD.org
Precedence: bulk

On May 30, Robert Schien <robsch@robkaos.ruhr.de> wrote:
> 
> I have an Archive Python DAT drive (28388-XXX.494) and want to turn
> off the compression mode. The reason is I get NCR timeout messages
> (there is a SC-200 in my P6NP5 system) when I write files to tape
> which are highly compressible. BTW, when this happens the DAT

Hmmm, I don't see how that could cause any problems!
I'm using an HP1533 DAT with compression enabled for 
all my backups, and it never showed the lightest 
problems ...

> is winded back and forth wildly and data which are on earlier

This winding forward and backward may indicate a drive
problem. Did you remember to clean the R/W head with
a cleaning cartridge, at least every 50 hours of use ?
(That may be 20 to 50 full backups, depending on your
system's specifics ...)

> sessions (or partitions or volumes, I don't know what the correct
> term is when you have miltiple parts on a tape) are destroyed. Two DAT tapes I
> have were so heavily trashed that the DAT drive refused even to to
> erase them. Here are some of the error messages:
> 
> May 29 13:46:21 robkaos /kernel: ncr0: have to clear fifos.
> May 29 13:46:21 robkaos /kernel: ncr0: restart (fatal error).

There should have been some (cryptic :) error message
above, which I guess might help.

> May 29 13:46:21 robkaos /kernel: st1: COMMAND FAILED (9 ff) @f0637800.
> May 29 13:46:27 robkaos /kernel: ncr0: timeout ccb=f0637800 (skip)
> May 29 13:47:24 robkaos /kernel: ncr0: timeout ccb=f0658e00 (skip)
> May 29 13:47:25 robkaos /kernel: st1: 5.0 MB/s (200 ns, offset 8)
> May 29 13:47:25 robkaos /kernel: sd1: 10.0 MB/s (100 ns, offset 8)

You got an IBM disk drive ? :)

> May 29 13:50:29 robkaos /kernel: ncr0: timeout ccb=f0658e00 (skip)
> May 29 13:50:30 robkaos /kernel: st1: MEDIUM ERROR asc:3,2 Excessive write errors

Well, this is not a driver message, but a message sent
by your drive !!!

> BTW, the DAT cartrdges ware brand new (Verbatim).
> 
> Robert 
> 
> P.S.: The system is -current (2 weeks old).

And the DAT drive ? :)

Guess you should first try cleaning your drive's heads.
As long as you get the MEDIUM ERROR messages, there is
no way I could do anything for you ...

Gruss, STefan