From: Robin Hill <robin@robinhill.me.uk>
To: "Karsten Römke" <k.roemke@gmx.de>
Cc: linux-raid@vger.kernel.org
Subject: Re: misunderstanding of spare and raid devices?
Date: Thu, 30 Jun 2011 11:58:40 +0100 [thread overview]
Message-ID: <20110630105840.GA27551@cthulhu.home.robinhill.me.uk> (raw)
In-Reply-To: <4E0C5539.4030000@gmx.de>
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On Thu Jun 30, 2011 at 12:51:37 +0200, Karsten Römke wrote:
> Hello,
> I'm searching some hours / minutes to create a raid5 device with 4
> disks and 1 spare:
> I tried first with the opensuse tool but no success as I want, so I
> tried mdadm
>
> Try:
> mdadm --create /dev/md0 --level=5 --raid-devices=4 --spare-devices=1
> /dev/sda3 /dev/sdb2 /dev/sdc5 /dev/sdd5 /dev/sde5
>
> leads to
> Personalities : [raid0] [raid1] [raid10] [raid6] [raid5] [raid4]
> md0 : active (auto-read-only) raid5 sdd5[5](S) sde5[4](S) sdc5[2] sdb2[1] sda3[0]
> 13759296 blocks level 5, 64k chunk, algorithm 2 [4/3] [UUU_]
>
> 2 spares - I don't understand that.
>
That's perfectly normal. The RAID5 array is created in degraded mode,
then recovered onto the final disk. That way it becomes available for
use immediately, rather than requiring all the parity to be calculated
before the array is ready. As it's been started in auto-read-only mode
(not sure why though) then it hasn't started recovery yet. Running
"mdadm -w /dev/md0" or mounting the array will kick it into read-write
mode and start the recovery process.
HTH,
Robin
--
___
( ' } | Robin Hill <robin@robinhill.me.uk> |
/ / ) | Little Jim says .... |
// !! | "He fallen in de water !!" |
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next prev parent reply other threads:[~2011-06-30 10:58 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-30 10:51 misunderstanding of spare and raid devices? Karsten Römke
2011-06-30 10:58 ` Robin Hill [this message]
2011-06-30 13:09 ` Karsten Römke
2011-06-30 11:30 ` John Robinson
2011-06-30 12:32 ` Phil Turmel
2011-06-30 12:52 ` misunderstanding of spare and raid devices? - and one question more Karsten Römke
2011-06-30 13:34 ` Phil Turmel
2011-06-30 14:05 ` Karsten Römke
2011-06-30 14:21 ` Karsten Römke
2011-06-30 14:44 ` Phil Turmel
2011-07-02 8:34 ` Karsten Römke
2011-07-02 9:42 ` David Brown
2011-06-30 21:28 ` NeilBrown
2011-07-01 7:23 ` David Brown
2011-07-01 8:50 ` Robin Hill
2011-07-01 10:18 ` David Brown
2011-07-01 11:29 ` Robin Hill
2011-07-01 12:45 ` David Brown
2011-07-01 13:02 ` NeilBrown
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