From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Majed B." Subject: Re: reconstruct raid superblock Date: Thu, 17 Dec 2009 13:35:23 +0300 Message-ID: <70ed7c3e0912170235m3af05859x9c0472d4c7d2f370@mail.gmail.com> References: <549053140912161953x665f84cbnc457c45e47ac2a97@mail.gmail.com> <70ed7c3e0912162117n3617556p3a8decef94f33a1c@mail.gmail.com> <70ed7c3e0912162121v5df1b972x6d9176bdf7e27401@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <70ed7c3e0912162121v5df1b972x6d9176bdf7e27401@mail.gmail.com> Sender: linux-raid-owner@vger.kernel.org To: Carl Karsten Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids I have misread the information you've provided, so allow me to correct = myself: You're running a RAID6 array, with 2 disks lost/failed. Any disk loss after that will cause data loss since you have no redundancy (2 disks died). I believe it's still possible to reassemble the array, but you only need to remove the MBR. See this page for information: http://www.cyberciti.biz/faq/linux-how-to-uninstall-grub/ dd if=3D/dev/null of=3D/dev/sdX bs=3D446 count=3D1 Before proceeding, provide the output of cat /proc/mdstat Is the array currently running degraded or is it suspended? What happened to the spare disk assigned? Did it finish resyncing before you installed grub on the wrong disk? On Thu, Dec 17, 2009 at 8:21 AM, Majed B. wrote: > If your other disks are sane and you are able to run a degraded array= ,=C2=A0 then > you can remove grub using dd then re-add the disk to the array. > > To clear the first 1MB of the disk: > dd if=3D/dev/zero of=3D/dev/sdx bs=3D1M count=3D1 > Replace sdx with the disk name that has grub. > > On Dec 17, 2009 6:53 AM, "Carl Karsten" wrot= e: > > I took over a box that had 1 ide boot drive, 6 sata raid drives (4 > internal, 2 external.) =C2=A0I believe the 2 externals were redundant= , so > could be removed. =C2=A0so I did, and mkfs-ed them. =C2=A0then I inst= alled > ubuntu to the ide, and installed grub to sda, which turns out to be > the first sata. =C2=A0which would be fine if the raid was on sda1, bu= t it > is on sda, and now the raid wont' assemble. =C2=A0no surprise, and I = do > have a backup of the data spread across 5 external drives. =C2=A0but = before > I =C2=A0abandon the array, I am wondering if I can fix it by recreati= ng > mdadm's metatdata on sda, given I have sd[bcd] to work with. > > any suggestions? > > root@dhcp128:~# mdadm --examine /dev/sd[abcd] > mdadm: No md superblock detected on /dev/sda. > /dev/sdb: > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0Magic : a92b4efc > =C2=A0 =C2=A0 =C2=A0 =C2=A0Version : 00.90.00 > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 UUID : 8d0cf436:3fc2d2ef:93d71b24:= b036cc6b > =C2=A0Creation Time : Wed Mar 25 21:04:08 2009 > =C2=A0 =C2=A0 Raid Level : raid6 > =C2=A0Used Dev Size : 1465137408 (1397.26 GiB 1500.30 GB) > =C2=A0 =C2=A0 Array Size : 5860549632 (5589.06 GiB 6001.20 GB) > =C2=A0 Raid Devices : 6 > =C2=A0Total Devices : 6 > Preferred Minor : 0 > > =C2=A0 =C2=A0Update Time : Tue Mar 31 23:08:02 2009 > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0State : clean > =C2=A0Active Devices : 5 > Working Devices : 6 > =C2=A0Failed Devices : 1 > =C2=A0Spare Devices : 1 > =C2=A0 =C2=A0 =C2=A0 Checksum : a4fbb93a - correct > =C2=A0 =C2=A0 =C2=A0 =C2=A0 Events : 8430 > > =C2=A0 =C2=A0 Chunk Size : 64K > > =C2=A0 =C2=A0 =C2=A0Number =C2=A0 Major =C2=A0 Minor =C2=A0 RaidDevic= e State > this =C2=A0 =C2=A0 6 =C2=A0 =C2=A0 =C2=A0 8 =C2=A0 =C2=A0 =C2=A0 16 =C2= =A0 =C2=A0 =C2=A0 =C2=A06 =C2=A0 =C2=A0 =C2=A0spare =C2=A0 /dev/sdb > > =C2=A0 0 =C2=A0 =C2=A0 0 =C2=A0 =C2=A0 =C2=A0 8 =C2=A0 =C2=A0 =C2=A0 = =C2=A00 =C2=A0 =C2=A0 =C2=A0 =C2=A00 =C2=A0 =C2=A0 =C2=A0active sync =C2= =A0 /dev/sda > =C2=A0 1 =C2=A0 =C2=A0 1 =C2=A0 =C2=A0 =C2=A0 8 =C2=A0 =C2=A0 =C2=A0 = 64 =C2=A0 =C2=A0 =C2=A0 =C2=A01 =C2=A0 =C2=A0 =C2=A0active sync =C2=A0 = /dev/sde > =C2=A0 2 =C2=A0 =C2=A0 2 =C2=A0 =C2=A0 =C2=A0 8 =C2=A0 =C2=A0 =C2=A0 = 32 =C2=A0 =C2=A0 =C2=A0 =C2=A02 =C2=A0 =C2=A0 =C2=A0active sync =C2=A0 = /dev/sdc > =C2=A0 3 =C2=A0 =C2=A0 3 =C2=A0 =C2=A0 =C2=A0 8 =C2=A0 =C2=A0 =C2=A0 = 48 =C2=A0 =C2=A0 =C2=A0 =C2=A03 =C2=A0 =C2=A0 =C2=A0active sync =C2=A0 = /dev/sdd > =C2=A0 4 =C2=A0 =C2=A0 4 =C2=A0 =C2=A0 =C2=A0 0 =C2=A0 =C2=A0 =C2=A0 = =C2=A00 =C2=A0 =C2=A0 =C2=A0 =C2=A04 =C2=A0 =C2=A0 =C2=A0faulty removed > =C2=A0 5 =C2=A0 =C2=A0 5 =C2=A0 =C2=A0 =C2=A0 8 =C2=A0 =C2=A0 =C2=A0 = 80 =C2=A0 =C2=A0 =C2=A0 =C2=A05 =C2=A0 =C2=A0 =C2=A0active sync > =C2=A0 6 =C2=A0 =C2=A0 6 =C2=A0 =C2=A0 =C2=A0 8 =C2=A0 =C2=A0 =C2=A0 = 16 =C2=A0 =C2=A0 =C2=A0 =C2=A06 =C2=A0 =C2=A0 =C2=A0spare =C2=A0 /dev/s= db > /dev/sdc: > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0Magic : a92b4efc > =C2=A0 =C2=A0 =C2=A0 =C2=A0Version : 00.90.00 > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 UUID : 8d0cf436:3fc2d2ef:93d71b24:= b036cc6b > =C2=A0Creation Time : Wed Mar 25 21:04:08 2009 > =C2=A0 =C2=A0 Raid Level : raid6 > =C2=A0Used Dev Size : 1465137408 (1397.26 GiB 1500.30 GB) > =C2=A0 =C2=A0 Array Size : 5860549632 (5589.06 GiB 6001.20 GB) > =C2=A0 Raid Devices : 6 > =C2=A0Total Devices : 4 > Preferred Minor : 0 > > =C2=A0 =C2=A0Update Time : Sun Jul 12 11:31:47 2009 > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0State : clean > =C2=A0Active Devices : 4 > Working Devices : 4 > =C2=A0Failed Devices : 2 > =C2=A0Spare Devices : 0 > =C2=A0 =C2=A0 =C2=A0 Checksum : a59452db - correct > =C2=A0 =C2=A0 =C2=A0 =C2=A0 Events : 580158 > > =C2=A0 =C2=A0 Chunk Size : 64K > > =C2=A0 =C2=A0 =C2=A0Number =C2=A0 Major =C2=A0 Minor =C2=A0 RaidDevic= e State > this =C2=A0 =C2=A0 2 =C2=A0 =C2=A0 =C2=A0 8 =C2=A0 =C2=A0 =C2=A0 32 =C2= =A0 =C2=A0 =C2=A0 =C2=A02 =C2=A0 =C2=A0 =C2=A0active sync =C2=A0 /dev/s= dc > > =C2=A0 0 =C2=A0 =C2=A0 0 =C2=A0 =C2=A0 =C2=A0 8 =C2=A0 =C2=A0 =C2=A0 = =C2=A00 =C2=A0 =C2=A0 =C2=A0 =C2=A00 =C2=A0 =C2=A0 =C2=A0active sync =C2= =A0 /dev/sda > =C2=A0 1 =C2=A0 =C2=A0 1 =C2=A0 =C2=A0 =C2=A0 0 =C2=A0 =C2=A0 =C2=A0 = =C2=A00 =C2=A0 =C2=A0 =C2=A0 =C2=A01 =C2=A0 =C2=A0 =C2=A0faulty removed > =C2=A0 2 =C2=A0 =C2=A0 2 =C2=A0 =C2=A0 =C2=A0 8 =C2=A0 =C2=A0 =C2=A0 = 32 =C2=A0 =C2=A0 =C2=A0 =C2=A02 =C2=A0 =C2=A0 =C2=A0active sync =C2=A0 = /dev/sdc > =C2=A0 3 =C2=A0 =C2=A0 3 =C2=A0 =C2=A0 =C2=A0 8 =C2=A0 =C2=A0 =C2=A0 = 48 =C2=A0 =C2=A0 =C2=A0 =C2=A03 =C2=A0 =C2=A0 =C2=A0active sync =C2=A0 = /dev/sdd > =C2=A0 4 =C2=A0 =C2=A0 4 =C2=A0 =C2=A0 =C2=A0 0 =C2=A0 =C2=A0 =C2=A0 = =C2=A00 =C2=A0 =C2=A0 =C2=A0 =C2=A04 =C2=A0 =C2=A0 =C2=A0faulty removed > =C2=A0 5 =C2=A0 =C2=A0 5 =C2=A0 =C2=A0 =C2=A0 8 =C2=A0 =C2=A0 =C2=A0 = 96 =C2=A0 =C2=A0 =C2=A0 =C2=A05 =C2=A0 =C2=A0 =C2=A0active sync > /dev/sdd: > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0Magic : a92b4efc > =C2=A0 =C2=A0 =C2=A0 =C2=A0Version : 00.90.00 > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 UUID : 8d0cf436:3fc2d2ef:93d71b24:= b036cc6b > =C2=A0Creation Time : Wed Mar 25 21:04:08 2009 > =C2=A0 =C2=A0 Raid Level : raid6 > =C2=A0Used Dev Size : 1465137408 (1397.26 GiB 1500.30 GB) > =C2=A0 =C2=A0 Array Size : 5860549632 (5589.06 GiB 6001.20 GB) > =C2=A0 Raid Devices : 6 > =C2=A0Total Devices : 4 > Preferred Minor : 0 > > =C2=A0 =C2=A0Update Time : Sun Jul 12 11:31:47 2009 > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0State : clean > =C2=A0Active Devices : 4 > Working Devices : 4 > =C2=A0Failed Devices : 2 > =C2=A0Spare Devices : 0 > =C2=A0 =C2=A0 =C2=A0 Checksum : a59452ed - correct > =C2=A0 =C2=A0 =C2=A0 =C2=A0 Events : 580158 > > =C2=A0 =C2=A0 Chunk Size : 64K > > =C2=A0 =C2=A0 =C2=A0Number =C2=A0 Major =C2=A0 Minor =C2=A0 RaidDevic= e State > this =C2=A0 =C2=A0 3 =C2=A0 =C2=A0 =C2=A0 8 =C2=A0 =C2=A0 =C2=A0 48 =C2= =A0 =C2=A0 =C2=A0 =C2=A03 =C2=A0 =C2=A0 =C2=A0active sync =C2=A0 /dev/s= dd > > =C2=A0 0 =C2=A0 =C2=A0 0 =C2=A0 =C2=A0 =C2=A0 8 =C2=A0 =C2=A0 =C2=A0 = =C2=A00 =C2=A0 =C2=A0 =C2=A0 =C2=A00 =C2=A0 =C2=A0 =C2=A0active sync =C2= =A0 /dev/sda > =C2=A0 1 =C2=A0 =C2=A0 1 =C2=A0 =C2=A0 =C2=A0 0 =C2=A0 =C2=A0 =C2=A0 = =C2=A00 =C2=A0 =C2=A0 =C2=A0 =C2=A01 =C2=A0 =C2=A0 =C2=A0faulty removed > =C2=A0 2 =C2=A0 =C2=A0 2 =C2=A0 =C2=A0 =C2=A0 8 =C2=A0 =C2=A0 =C2=A0 = 32 =C2=A0 =C2=A0 =C2=A0 =C2=A02 =C2=A0 =C2=A0 =C2=A0active sync =C2=A0 = /dev/sdc > =C2=A0 3 =C2=A0 =C2=A0 3 =C2=A0 =C2=A0 =C2=A0 8 =C2=A0 =C2=A0 =C2=A0 = 48 =C2=A0 =C2=A0 =C2=A0 =C2=A03 =C2=A0 =C2=A0 =C2=A0active sync =C2=A0 = /dev/sdd > =C2=A0 4 =C2=A0 =C2=A0 4 =C2=A0 =C2=A0 =C2=A0 0 =C2=A0 =C2=A0 =C2=A0 = =C2=A00 =C2=A0 =C2=A0 =C2=A0 =C2=A04 =C2=A0 =C2=A0 =C2=A0faulty removed > =C2=A0 5 =C2=A0 =C2=A0 5 =C2=A0 =C2=A0 =C2=A0 8 =C2=A0 =C2=A0 =C2=A0 = 96 =C2=A0 =C2=A0 =C2=A0 =C2=A05 =C2=A0 =C2=A0 =C2=A0active sync > > -- > Carl K > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid"= in > the body of a message to majordomo@vger.kernel.org > More majordomo info at =C2=A0http://vger.kernel.org/majordomo-info.ht= ml > --=20 Majed B. -- 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