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From: Neil Brown <neilb@cse.unsw.edu.au>
To: William Thompson <wt@electro-mechanical.com>
Date: Fri, 21 Jun 2002 12:51:40 +1000 (EST)
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Message-ID: <15634.38076.959047.462763@notabene.cse.unsw.edu.au>
Cc: linux-kernel@vger.kernel.org
Subject: Re: partition md raid?
In-Reply-To: message from William Thompson on Wednesday June 19
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On Wednesday June 19, wt@electro-mechanical.com wrote:
> Is this possible (w/o using lvm)

Yes, but you need a patch...
http://www.cse.unsw.edu.au/~neilb/patches/linux-stable/
 2.4.19-pre8 section
      patch-Z-MdLocks
            Improve locking of MD related structure, particularly when reconfiguring 
      patch-a-RaidSplit
            Split raid requests that span chunks 
      patch-b-MdPart
            Enable partitioning of MD devices 
      patch-c-MdpMajor
            Define a static major number for mdp - partitioned md 

These patches should make the first 16 devices partitionable.
Without patch-c-MdpMajor, a free major number is allocated (usually
254, but no guarantees) and you have to either:
 - have a script which finds the number from /proc/devices and makes
   all the /dev entries, or
 - use devfs

With patch-c-MdpMajor, Major number "60" (LOCAL/EXPERIMENTAL USE) is
allocated for the partitioned md devices.

I use this in production.  I have two system discs (sda and sdb, or
hda and hdc) which are mirrored together as whole devices, and then
this is partitioned:
   mda1 == root
   mda2 == swap
   mda3 == other...

Getting lilo to cope was interesting, but it works.

NeilBrown
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