Subject: Re: Dynamic SCSI ids (was: A possible way of handling...)
To: Johan Danielsson <>
From: Curt Sampson <>
List: tech-kern
Date: 03/30/1997 00:22:31
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On 30 Mar 1997, Johan Danielsson wrote:

> SCSI 1 goes kaput, which causes a panic. The system reboots and then
> magically SCSI 2 will be sd1, and fsck has a nice opportunity to mess
> things up bad.
> If I don't remember wrong, this did happen with some version of 4.3
> which had static geometry information, `gee, this is sd1, and I know
> it's *this* big', so you always had an extra lost disk, if you weren't
> quick enough.

We don't use compiled-in geometry information anymore, and the
disklabel now has filesystem information for each partition. If
fsck_ffs will even think about attempting to work on a partition
that isn't marked `4.2BSD', it's rather broken, and fixing that is
the correct solution.

Yes, I suppose you could have a disk where the disklabel section
just happens to checksum just like a BSD disklabel, and it might
just happen to have what appears to be partition information and
a 4.2BSD parition in it that matches one from the dead disk (so it
appears in /etc/fstab), and it could look like such a lightly
damaged FFS filesystem that fsck tries to fix it, rather than just
choking completely. Just possibly, I suppose.


Curt Sampson		Info at
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