From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicolas Jungers Subject: Re: RAID5 disk failure during rebuild of spare, any chance of recovery when one of the failed devices is suspected to be intact? Date: Mon, 16 Aug 2010 08:12:35 +0200 Message-ID: <4C68D6D3.6070906@jungers.net> References: <4C68CCC9.2050604@jungers.net> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: linux-raid Cc: =?UTF-8?B?VG9yIEFybmUgVmVzdGLDuA==?= List-Id: linux-raid.ids On 08/16/2010 07:54 AM, Tor Arne Vestb=C3=B8 wrote: > Hey Nicolas! > > On Mon, Aug 16, 2010 at 7:29 AM, Nicolas Jungers= wrote: >> I'd try to recreate the array with a copy of the disks >> >> do a ddrescue of the 3 good disks and then try a mdadm -C with the e= xact >> parameters of the array creation with the same mdadm version (use mi= ssing >> for slot 2). It saved my raid10 array. > > You mean you sdc and sde plus either sdb or sdd, depending on which > one I think is more sane a this point? I'd try both. Do a ddrescue of the failing one and try that (with copy= =20 of the others) and check what's coming out. > > mdadm -E before http://pastebin.com/f46EWXEA vs after > http://pastebin.com/Kp145Mkx indicates sdb1 is missing a few events, > dunno if that's too much to be usable at this point? Did write happen during the reconstruction? You'll lose not only what=20 was on the write but also everything on the same strip, including=20 directories. That's a reason to try with a copy of sdd. > Can the create-process be done "read-only", so that I don't have to > use extra disks? If I've understood things correctly --create will > only overwrite the superblocks, not touch the data? yes, but I'd not do it. And beside, you should not trust the failing=20 one (sdd). > > So I could do: > > mdadm -C /dev/md0 /dev/sdb1 /dev/sdc1 misssing /dev/sde1 or even mdadm -C /dev/md0 /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde1 with copies. > > I suppose the 33% restored spare sdf1 won't help any in this situatio= n? I suppose not. N. > > Tor Arne -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html