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From: Julian Elischer <julian@jules.DIALix.oz.au>
Message-Id: <199501051421.OAA00515@jules.DIALix.oz.au>
Subject: Re: Bad sectors on SCSI drive!
To: dufault@hda.com (Peter Dufault)
Date: Thu, 5 Jan 1995 14:21:46 +0000 ()
Cc: jkh@time.cdrom.com, mtaylor@gateway.cybernet.com, hackers@FreeBSD.org
In-Reply-To: <199501041055.FAA01628@hda.com> from "Peter Dufault" at Jan 4, 95 05:55:38 am
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> 
> Jordan K. Hubbard writes:
> > 
> > > Allright, so what can be done?  How can I map out bad sectors on a scsi
> > > drive?  Do I have to newfs the drive?
> > 
> > Return it to the manufacturer.  A good SCSI drive shouldn't develop faults
> > like this, and when it does, it's time to shoot it.
> 
> If you can't return the drive:
> 
> I don't think Jordan's statement is universally true.  Mode page
> 1 for a direct access device has a "AWRE" (automatic write
> reallocation) and "ARRE" (automatic read reallocation) selections
> that can be turned on and off.
> 
> I'm not sure why these would be turned off.
> 
> Also the spec reads that the automatic reallocation will be performed
> only if the target has the valid data.  Maybe on some drives there
> are circumstances where that can happen.

when the read error is sobad it can't be reconstructed by the
drive......
> 
> If you're running -current you can apply the patches in
> freefall:pub/incoming/sutar7.gz , rebuild the kernel and run the
> "ssec" command to slip the sectors by block number and the "mode_sense"
> command to see what the mode page settings are.
this command is in the driver... just needs an ioctl to call it......

of course then you have a bad block in a file..
use tar cf /dev/null /  to find the bad file BEFORE you fix the error
the bad file will be mentionned on stderr..

otherwise you'll never know which file is corruptted with a block of
nulls in  it's middle..

> 

julian