From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andy Smith <andy@strugglers.net>
Subject: Re: Shrinking number of devices on a RAID-10 (near 2) array
Date: Fri, 29 Aug 2014 04:42:26 +0000
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To: NeilBrown <neilb@suse.de>
Cc: linux-raid@vger.kernel.org
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Hi Neil,

On Fri, Aug 29, 2014 at 02:35:28PM +1000, NeilBrown wrote:
> On Fri, 29 Aug 2014 04:26:18 +0000 Andy Smith <andy@strugglers.net> wrote:
> > Sorry, still no joy:
> > 
> > # echo 309363696 > /sys/block/md2/md/dev-sda3/size
> > # cat /sys/block/md2/md/dev-sda3/size
> > 309363264
> 
> Try use "/bin/echo" so you get an error message.
> Also try smaller numbers.  Can you write anything larger than what is already
> there?  Increasing by 64 (match the 128 sectors that mdadm wants for
> new_offset) should  be enough.

I can't even increase it by 64 from what it is now:

# /bin/echo 309363328 > /sys/block/md2/md/dev-sda3/size
# cat /sys/block/md2/md/dev-sda3/size
309363264

In fact I can't increase it by 1, and /bin/echo doesn't say why.

Cheers,
Andy