From: NeilBrown <neilb@suse.de>
To: Brad Campbell <lists2009@fnarfbargle.com>
Cc: linux-raid@vger.kernel.org
Subject: Re: Couple of questions.
Date: Sun, 10 Apr 2011 18:02:54 +1000 [thread overview]
Message-ID: <20110410180254.5d59696a@notabene.brown> (raw)
In-Reply-To: <4DA08600.5020604@fnarfbargle.com>
On Sun, 10 Apr 2011 00:14:56 +0800 Brad Campbell <lists2009@fnarfbargle.com>
wrote:
> 1 - When adding 2 missing disks to a RAID-6 (let's say a 4 drive RAID-6
> that was created with only 2 disks initally) why does it sync the first,
> then sync the second rather than doing both together?
> ie mdadm --add /dev/md0 /dev/sd[ab]
Because the devices are added one at a time and between the moment when sda
is added and when sdb is added a recovery starts.
mdadm should write 'frozen' the 'sync_action' before adding the devices, and
then 'idle' after adding them both. But it doesn't yet.
You could...
echo frozen > /sys/block/md0/md/sync_action
mdadm /dev/md0 --add /dev/sd[ab]
echo idle > /sys/block/md0/md/sync_action
NeilBrown
>
> 2 - If a drive disappears how do I remove it from an array.
> Let's say I have a 10 drive RAID-6 that has an odd error on a disk.
> The disk goes away (sdl), the disk comes back as sdq as md is still
> hanging on to the name sdl. I add sdq to the array, but I can't remove
> sdl as it physically no longer exists. udev has removed the device node
> and mdadm can't remove it from the array as it can't tell what it was.
>
> Like this :
> Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4]
> md0 : active raid6 sdq[10] sdc[0] sdd[6] sdl[1](F) sdh[9] sda[8] sde[7]
> sdg[5] sdb[4] sdf[3] sdm[2]
> 7814078464 blocks super 1.2 level 6, 64k chunk, algorithm 2
> [10/10] [UUUUUUUUUU]
>
> Nothing urgent, just musings after the last weeks oddities.
>
> Regards,
> Brad
> --
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prev parent reply other threads:[~2011-04-10 8:02 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-09 16:14 Couple of questions Brad Campbell
2011-04-09 23:17 ` Roman Mamedov
2011-04-10 8:02 ` NeilBrown [this message]
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