From mboxrd@z Thu Jan  1 00:00:00 1970
From: Alex Lilley <alex@redwax.co.uk>
Subject: Re: status of raid 4/5 disk reduce
Date: Tue, 09 Dec 2008 21:11:30 +0000
Message-ID: <493EDF02.5090500@redwax.co.uk>
References: <493D8A95.2020700@mikebrancato.com>
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To: Michael Brancato <mike@mikebrancato.com>
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Hi Michael

I posed this a few weeks back but haven't seen any activity on it yet or 
any suggestion as to when this might be possible.

For reference, my thread started here: 
http://marc.info/?l=linux-raid&m=122753511309332&w=2

Cross fingers for this because I think it is a real killer feature.

Regards

Alex

Michael Brancato wrote:
> I'm curious as to the status of the ability to reduce the number of 
> disks in a RAID 4/5 array.  I would like the ability to reshape a 4 
> disk raid4/5 to a 3 disk raid4/5 for flexibility.
>
> here is what I want to do....
> $ sudo mdadm /dev/md0 --fail /dev/disk4 --remove /dev/disk4
> mdadm: set /dev/disk4 faulty in /dev/md0
> mdadm: hot removed /dev/disk4
> $ sudo mdadm --grow /dev/md0 -n3
> mdadm: /dev/md0: Cannot reduce number of data disks (yet).
>
> I know this capability is missing in the md driver.  What is needed to 
> make it work and is anyone currently working on it?
>
> Regards,
>