From: Martin Wilck <mwilck@arcor.de>
To: Francis Moreau <francis.moro@gmail.com>
Cc: linux-raid <linux-raid@vger.kernel.org>
Subject: Re: mdadm 3.3 fails to kick out non fresh disk
Date: Fri, 20 Sep 2013 20:07:53 +0200 [thread overview]
Message-ID: <523C8EF9.60809@arcor.de> (raw)
In-Reply-To: <CAC9WiBjnM5nwKf4f7UN6hQgsbYhVLLPnfAD6RATbF3C-NHRrXg@mail.gmail.com>
On 09/20/2013 10:56 AM, Francis Moreau wrote:
> Hello Martin,
>
> On Mon, Sep 16, 2013 at 7:04 PM, Martin Wilck <mwilck@arcor.de> wrote:
>> On 09/16/2013 03:56 PM, Francis Moreau wrote:
>>
>>> I did give your patch "DDF: compare_super_ddf: fix sequence number
>>> check" a try and now mdadm is able to detect a difference between the
>>> 2 disks. Therefore it refuses to insert the second disk which is
>>> better.
>>>
>>> However it's still not able to detect which version is the "fresher"
>>> like mdadm does with soft RAID1 (metadata 1.2). Therefore mdadm is not
>>> able to kick out the first disk if it's the outdated one.
>>>
>>> Is that expected ?
>>
>> At the moment, yes. This needs work.
>>
>
> Actually this is worse than I thought: with your patch applied mdadm
> refuses to add back a spare disk into a degraded DDF array.
>
> For example on a DDF array:
>
> # cat /proc/mdstat
> Personalities : [raid1]
> md126 : active raid1 sdb[1] sda[0]
> 2064384 blocks super external:/md127/0 [2/2] [UU]
>
> md127 : inactive sdb[1](S) sda[0](S)
> 65536 blocks super external:ddf
>
> unused devices: <none>
>
> # mdadm /dev/md126 --fail sdb
> [ 24.118434] md/raid1:md126: Disk failure on sdb, disabling device.
> [ 24.118437] md/raid1:md126: Operation continuing on 1 devices.
> mdadm: set sdb faulty in /dev/md126
>
> # mdadm /dev/md127 --remove sdb
> mdadm: hot removed sdb from /dev/md127
>
> # mdadm /dev/md127 --add /dev/sdb
> mdadm: added /dev/sdb
>
> # cat /proc/mdstat
> Personalities : [raid1]
> md126 : active raid1 sda[0]
> 2064384 blocks super external:/md127/0 [2/1] [U_]
>
> md127 : inactive sdb[1](S) sda[0](S)
> 65536 blocks super external:ddf
>
> unused devices: <none>
>
>
> As you can see the reinserted disk sdb sits as spare and isn't added
> back to the array.
That's correct. You marked that disk failed.
> Is it possible to add this major feature work again and keep your improvement ?
No. A failed disk can't be added again without rebuild. I am positive
about that.
Martin
>
> Thanks
next prev parent reply other threads:[~2013-09-20 18:07 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-13 13:22 mdadm 3.3 fails to kick out non fresh disk Francis Moreau
2013-09-13 20:43 ` NeilBrown
2013-09-13 22:35 ` Francis Moreau
2013-09-13 23:56 ` Roberto Spadim
2013-09-14 10:38 ` NeilBrown
2013-09-14 14:33 ` Francis Moreau
2013-09-14 15:06 ` Francis Moreau
2013-09-14 20:43 ` Martin Wilck
2013-09-16 13:56 ` Francis Moreau
2013-09-16 17:04 ` Martin Wilck
2013-09-20 8:56 ` Francis Moreau
2013-09-20 18:07 ` Martin Wilck [this message]
2013-09-20 21:08 ` Francis Moreau
2013-09-21 13:22 ` Francis Moreau
2013-09-23 20:02 ` Martin Wilck
2013-09-27 8:26 ` Francis Moreau
2013-09-27 15:47 ` Francis Moreau
2013-10-02 18:33 ` Martin Wilck
2013-10-16 4:57 ` NeilBrown
2013-10-16 20:10 ` Francis Moreau
2013-10-17 10:58 ` NeilBrown
2013-10-19 20:21 ` Martin Wilck
2013-10-20 23:59 ` NeilBrown
2013-09-24 17:38 ` Martin Wilck
2013-09-24 17:43 ` Martin Wilck
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