From: NeilBrown <neilb@suse.de>
To: Keith Keller <kkeller@wombat.san-francisco.ca.us>
Cc: linux-raid@vger.kernel.org
Subject: Re: raid 5 to raid 6 reshape gone bad
Date: Sun, 13 Nov 2011 14:55:56 +1100 [thread overview]
Message-ID: <20111113145556.45b04397@notabene.brown> (raw)
In-Reply-To: <4dq3p8xsef.ln2@goaway.wombat.san-francisco.ca.us>
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On Sat, 12 Nov 2011 19:33:24 -0800 Keith Keller
<kkeller@wombat.san-francisco.ca.us> wrote:
> On 2011-11-13, Travis Brown <teb@jetcom.org> wrote:
> > I was reshaping my 5 drive raid 5 with spare to a raid 6 array when the drive I was using for my backup went offline. If that's not murphy's law, I don't know what is. The array is still up and usable, but I'm afraid to reboot or doing anything to it, really. Suggestions on getting this thing back to usable are very welcome.
>
> > Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
> > md126 : active raid6 sde3[0] sdf3[3] sdb3[1] sdd3[4] sdc3[2]
> > 5856728064 blocks super 0.91 level 6, 512k chunk, algorithm 18 [5/4] [UUUU_]
>
> Do you have hot-swap drives? If so, simply mark sdd3 as faulty with
> mdadm, remove it from the array, then physically remove and replace it
> and use mdadm to add the new drive. The raid6 should start to rebuild
> automatically.
Not good advice. This is about reshaping, not rebuilding.
I'm sorry, but I think you've completely missed the point.
NeilBrown
>
> If you don't have hot-swap drives, you should still be able to use mdadm
> to set faulty and remove sdd3, shut down, replace sdd, and reboot. Make
> sure your /etc/mdadm.conf file is up to date and accurate before
> shutting down. Alternatively, make sure mdadm *won't* probe for raid
> arrays, and instead assemble it manually after booting; that might be a
> more sure way to do it. Either way, with four working disks your new
> raid6 can still suffer one more drive failure and still be usable.
>
> Of course, insert the standard disclaimer about RAID not being a
> replacement for backups. :) If it won't take too long, you might
> consider doing and/or refreshing your backups before attempting
> anything. (The hot-swap method is reasonably safe as long as you're
> *positive* you're removing the correct disk.)
>
> --keith
>
>
>
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next prev parent reply other threads:[~2011-11-13 3:55 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-13 2:56 raid 5 to raid 6 reshape gone bad Travis Brown
2011-11-13 3:33 ` Keith Keller
2011-11-13 3:55 ` Keith Keller
2011-11-13 3:55 ` NeilBrown [this message]
2011-11-13 3:35 ` NeilBrown
2011-11-13 13:11 ` Travis Brown
2011-11-13 13:50 ` Travis Brown
2011-11-13 14:53 ` Travis Brown
2011-11-14 6:07 ` NeilBrown
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