From: NeilBrown <neilb@suse.de>
To: Oliver Martin <oliver@volatilevoid.net>
Cc: linux-raid@vger.kernel.org
Subject: Re: Creating a 3-disk RAID6 array
Date: Thu, 17 May 2012 11:38:17 +1000 [thread overview]
Message-ID: <20120517113817.7faf9c1e@notabene.brown> (raw)
In-Reply-To: <4FB4534A.5070608@volatilevoid.net>
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On Thu, 17 May 2012 03:24:26 +0200 Oliver Martin <oliver@volatilevoid.net>
wrote:
> Hi,
>
> is there any specific reason why md refuses to create a RAID6 array with
> 3 disks? My (probably naive) understanding suggests it should be the
> same as a 3-disk RAID1, similar to a 2-disk RAID5.
I'll have to leave for for hpa to answer. I've occasionally thought that
maybe it should be fixed, but it never seemed worth the effort.
>
> The reason I'm asking is that I currently have space on three disks for
> a new array, and would like to expand it when I add a fourth. I tried
> this scenario with a few loopback devices, but the only way to go from a
> 3-disk RAID1 to a 4-disk RAID6 seems to be via an intermediate 3-disk
> RAID5, requiring two reshapes. I'd like to avoid one of them, if at all
> possible.
Yes, not possible at present.
It might be as simple and finding the places that impose the limit and delete
them...
NeilBrown
>
> Regards,
> Oliver
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next prev parent reply other threads:[~2012-05-17 1:38 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-17 1:24 Creating a 3-disk RAID6 array Oliver Martin
2012-05-17 1:38 ` NeilBrown [this message]
2012-05-17 13:18 ` David Brown
2012-05-17 14:04 ` John Robinson
2012-05-18 7:24 ` David Brown
2012-05-18 7:30 ` H. Peter Anvin
2012-05-18 7:57 ` NeilBrown
2012-05-19 0:04 ` H. Peter Anvin
2012-05-17 21:02 ` Dan Williams
2012-05-17 23:27 ` Oliver Martin
2012-05-17 4:22 ` Bill Davidsen
2012-05-18 2:36 ` Stan Hoeppner
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