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From: Wols Lists <antlists@youngman.org.uk>
To: Dave Chinner <david@fromorbit.com>
Cc: linux-xfs@vger.kernel.org, linux-raid@vger.kernel.org
Subject: Re: Growing RAID10 with active XFS filesystem
Date: Tue, 9 Jan 2018 09:36:49 +0000	[thread overview]
Message-ID: <5A548D31.4000002@youngman.org.uk> (raw)
In-Reply-To: <20180108220139.GB16421@dastard>

On 08/01/18 22:01, Dave Chinner wrote:
> Yup, 21 devices in a RAID 10. That's a really nasty config for
> RAID10 which requires an even number of disks to mirror correctly.
> Why does MD even allow this sort of whacky, sub-optimal
> configuration?

Just to point out - if this is raid-10 (and not raid-1+0 which is a
completely different beast) this is actually a normal linux config. I'm
planning to set up a raid-10 across 3 devices. What happens is that is
that raid-10 writes X copies across Y devices. If X = Y then it's a
normal mirror config, if X > Y it makes good use of space (and if X < Y
it doesn't make sense :-)

SDA: 1, 2, 4, 5

SDB: 1, 3, 4, 6

SDC: 2, 3, 5, 6

Cheers,
Wol

  parent reply	other threads:[~2018-01-09  9:44 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-08 19:08 Growing RAID10 with active XFS filesystem xfs.pkoch
2018-01-08 19:26 ` Darrick J. Wong
2018-01-08 22:01   ` Dave Chinner
2018-01-08 23:44     ` xfs.pkoch
2018-01-09  9:36     ` Wols Lists [this message]
2018-01-09 21:47       ` IMAP-FCC:Sent
2018-01-09 22:25       ` Dave Chinner
2018-01-09 22:32         ` Reindl Harald
2018-01-10  6:17         ` Wols Lists
2018-01-11  2:14           ` Dave Chinner
2018-01-12  2:16             ` Guoqing Jiang
2018-01-10 14:10         ` Phil Turmel
2018-01-11  3:07           ` Dave Chinner
2018-01-12 13:32             ` Wols Lists
2018-01-12 14:25               ` Emmanuel Florac
2018-01-12 17:52                 ` Wols Lists
2018-01-12 18:37                   ` Emmanuel Florac
2018-01-12 19:35                     ` Wol's lists
2018-01-13 12:30                       ` Brad Campbell
2018-01-13 13:18                         ` Wols Lists
2018-01-13  0:20                   ` Stan Hoeppner
2018-01-13 19:29                     ` Wol's lists
2018-01-13 22:40                       ` Dave Chinner
2018-01-13 23:04                         ` Wols Lists
2018-01-14 21:33                 ` Wol's lists
2018-01-15 17:08                   ` Emmanuel Florac

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