Subject: Re: misunderstood SCSI failure with Adaptec 2842VL controller
To: None <>
From: der Mouse <mouse@Holo.Rodents.Montreal.QC.CA>
List: current-users
Date: 11/27/1996 13:46:00
> I have an Archive 150 tape drive talking to an Adaptec 2842VL
> controller.  Tar seems to write the tape o.k. until it wants to close
> the device.  I get:

> 	tar (child): can't write to /dev/rst0 : Input/output error

> And in messages I get:

> 	Nov 24 10:08:19 dakkon /netbsd: st0: bad request, must be multiple of 512

> What does this mean???

It means tar tried a write() operation with a size that is not a
multiple of 512, as the kernel message says.  QIC tapes do not fit the
traditional UNIX tape model of streams of records with filemarks (with
some record size limits, usually 0<=size<=63k or some such); instead,
they are streams of 512-byte blocks with filemarks.

Why this is happening is another story.  What tar command line are you
using?  A tar archive is always a multiple of 512 bytes long, so either
there's a critical bug in tar or something else is happening - I think
NetBSD uses GNU tar; are you using the z option, which causes tar to
gzip the archive?  I suspect tar doesn't pad and reblock the gzipped
output if you do that (which is arguably a, bug but that's neither here
nor there at the moment).

					der Mouse

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