[5138] in linux-scsi channel archive
Re: Scsi tape - returns ENXIO after an error (aha1542 + others)[PATCH]
daemon@ATHENA.MIT.EDU (Kai M{kisara)
Sun Nov 15 03:19:54 1998
Date: Sun, 15 Nov 1998 10:16:15 +0200 (EET)
From: Kai M{kisara <makisara@metla.fi>
Reply-To: Kai.Makisara@metla.fi
To: Richard Fish <rjf@estinc.com>
cc: linux-scsi@vger.rutgers.edu
In-Reply-To: <364DDC81.E769B575@estinc.com>
On Sat, 14 Nov 1998, Richard Fish wrote:
> Kai M{kisara wrote:
> >
...
> With tape drives, the error handling appears to BE the problem. First,
> it can't "fix" the original problem, so the end result is that the drive
> is taken offline. The lowlevel scsi module must then be reloaded in
> order for the drive to be usable again. And if you happen to use the
> non-rewinding device to put multiple archives on a tape, you will never
> be able to access anything but the first archive. This is VERY bad!
>
There are two problems in the new error handling with tapes (an probably
with other devices, too):
1. It does not pass up to the tape driver some sense returns that
actually are not errors with respect to tapes (the condition bits,
BLANK CHECK). For most other devices CHECK CONDITION means a problem. With
tapes some of these are encountered in normal operation.
2. It seems to be too eager to try to correct problems with bus resets.
...
> > following is just speculation. The function scsi_check_sense() returns
> > SUCCESS in case of UNIT_ATTENTION and the comment says that in this case
> > the the information is passed up to the upper level driver. This is what
> > want to happen with FM, EOM, and ILI. If the test near the beginning of
> > the function is changed to
> >
> > if (SCpnt->sense_buffer[2] & 0xe0)
> > return FAILED;
^^^^^^
You are correct, this should have been SUCCESS (I copied the current
code but forgot to edit it).
I will try to find some time to read the code tonight to see if this is
the correct fix (but still hoping that someone knowing the new error
handling would step up and say what is the correct thing to do ;-)
Kai
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