From mboxrd@z Thu Jan  1 00:00:00 1970
From: John Robinson <john.robinson@anonymous.org.uk>
Subject: Re: Is shrinking raid5 possible?
Date: Fri, 06 Nov 2009 18:32:15 +0000
Message-ID: <4AF46BAF.3020900@anonymous.org.uk>
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To: Thomas Arthur Oehser <tom@toms.net>
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On 06/11/2009 13:17, Thomas Arthur Oehser wrote:
[...]
>  - resize2fs /dev/md3 <smaller>
>  - mdadm -G -z <smaller> /dev/md3
>  - fdisk /dev/sd[a-c]3 <smaller>
> 
> It _almost_ works fine... but... the mdadm -G keeps the (0.90) superblock
> at the _end_ of the _device_ ... which hasn't been resized yet ...
> 
> How do I put the superblock back after fdisk, or make -G move or recreate?

Are you sure it hasn't already put a copy of the superblock in the right 
place, within the <smaller> size, as well as leaving a copy at the end 
of the original larger partition? That's what I would do if I was the 
author, so the partition can still be recognised as a md one before the 
partition is resized; you wouldn't want the parition to become 
unrecognisable or unusable.

Cheers,

John.