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Date: Wed, 15 Oct 1997 09:00:45 +1000
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199710142300.JAA27330@godzilla.zeta.org.au>
To: perhaps@yes.no, Shimon@i-Connect.Net
Subject: RE: adding RAID to the OS without re-partitioning
Cc: freebsd-fs@FreeBSD.ORG, freebsd-scsi@FreeBSD.ORG, greg@lightningweb.com
Sender: owner-freebsd-scsi@FreeBSD.ORG
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>[Long and complicated description deleted]
>
>This use an MS-DOS partition table, and is not how I would have done
>it - I would have done
>
>## Find SCSI device number
>$ dmesg | grep sd
>sd17(dpt0:1:0): Direct-Access 16394MB (32542592 528 byte sectors)
>
>## Initial labelling of disk
>$ disklabel -rw sd17 auto

If there is already a DOS partition (slice) table, then this won't
work.  I recently fixed a bug that allowed disklabel on an empty BSD
compatibility slice to corrupt the slice table.  Empty BSD compatibility
slices occur naturally on all disks that have a slice table but don't
have a BSD slice.

You should remove the partition table using
$ dd if=/dev/zero of=/dev/rsd17 count=1
before running disklabel.  It may also be necessary to remove a stale
label in the second sector of the disk by using a count of 2 instead
of 1.  You should check existing partition tables and labels before
removing them.

>(you'll likely get a warning about "wrong magic number" in the syslog
>about here - ignore it)

Someone recently removed the warning.  Previously, if you didn't get
the warning, it meant that there was a probably a partition table and
you should have been careful removing it :-).

>...
>And now just mount them.  (Shimon was more detailed - I just say that
>this is described both in the handbook and the FAQ ;-)

I think the dd step is described there.

Bruce