From mboxrd@z Thu Jan 1 00:00:00 1970 From: Carl Karsten Subject: Re: reconstruct raid superblock Date: Thu, 17 Dec 2009 00:18:21 -0600 Message-ID: <549053140912162218g1620a2e5oe7e7188ef27df282@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=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <70ed7c3e0912162121v5df1b972x6d9176bdf7e27401@mail.gmail.com> Sender: linux-raid-owner@vger.kernel.org To: "Majed B." Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids A degraded array is just missing the redundant data, not needed data, r= ight? I am pretty sure I need all 4 disks. Is there any reason to 0 out the bytes I want replaced with good bytes? On Wed, Dec 16, 2009 at 11:21 PM, Majed B. wrote: > If your other disks are sane and you are able to run a degraded array= ,=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.) =A0I believe the 2 externals were redundant, s= o > could be removed. =A0so I did, and mkfs-ed them. =A0then I installed > ubuntu to the ide, and installed grub to sda, which turns out to be > the first sata. =A0which would be fine if the raid was on sda1, but i= t > is on sda, and now the raid wont' assemble. =A0no surprise, and I do > have a backup of the data spread across 5 external drives. =A0but bef= ore > I =A0abandon the array, I am wondering if I can fix it by recreating > 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: > =A0 =A0 =A0 =A0 =A0Magic : a92b4efc > =A0 =A0 =A0 =A0Version : 00.90.00 > =A0 =A0 =A0 =A0 =A0 UUID : 8d0cf436:3fc2d2ef:93d71b24:b036cc6b > =A0Creation Time : Wed Mar 25 21:04:08 2009 > =A0 =A0 Raid Level : raid6 > =A0Used Dev Size : 1465137408 (1397.26 GiB 1500.30 GB) > =A0 =A0 Array Size : 5860549632 (5589.06 GiB 6001.20 GB) > =A0 Raid Devices : 6 > =A0Total Devices : 6 > Preferred Minor : 0 > > =A0 =A0Update Time : Tue Mar 31 23:08:02 2009 > =A0 =A0 =A0 =A0 =A0State : clean > =A0Active Devices : 5 > Working Devices : 6 > =A0Failed Devices : 1 > =A0Spare Devices : 1 > =A0 =A0 =A0 Checksum : a4fbb93a - correct > =A0 =A0 =A0 =A0 Events : 8430 > > =A0 =A0 Chunk Size : 64K > > =A0 =A0 =A0Number =A0 Major =A0 Minor =A0 RaidDevice State > this =A0 =A0 6 =A0 =A0 =A0 8 =A0 =A0 =A0 16 =A0 =A0 =A0 =A06 =A0 =A0 = =A0spare =A0 /dev/sdb > > =A0 0 =A0 =A0 0 =A0 =A0 =A0 8 =A0 =A0 =A0 =A00 =A0 =A0 =A0 =A00 =A0 =A0= =A0active sync =A0 /dev/sda > =A0 1 =A0 =A0 1 =A0 =A0 =A0 8 =A0 =A0 =A0 64 =A0 =A0 =A0 =A01 =A0 =A0= =A0active sync =A0 /dev/sde > =A0 2 =A0 =A0 2 =A0 =A0 =A0 8 =A0 =A0 =A0 32 =A0 =A0 =A0 =A02 =A0 =A0= =A0active sync =A0 /dev/sdc > =A0 3 =A0 =A0 3 =A0 =A0 =A0 8 =A0 =A0 =A0 48 =A0 =A0 =A0 =A03 =A0 =A0= =A0active sync =A0 /dev/sdd > =A0 4 =A0 =A0 4 =A0 =A0 =A0 0 =A0 =A0 =A0 =A00 =A0 =A0 =A0 =A04 =A0 =A0= =A0faulty removed > =A0 5 =A0 =A0 5 =A0 =A0 =A0 8 =A0 =A0 =A0 80 =A0 =A0 =A0 =A05 =A0 =A0= =A0active sync > =A0 6 =A0 =A0 6 =A0 =A0 =A0 8 =A0 =A0 =A0 16 =A0 =A0 =A0 =A06 =A0 =A0= =A0spare =A0 /dev/sdb > /dev/sdc: > =A0 =A0 =A0 =A0 =A0Magic : a92b4efc > =A0 =A0 =A0 =A0Version : 00.90.00 > =A0 =A0 =A0 =A0 =A0 UUID : 8d0cf436:3fc2d2ef:93d71b24:b036cc6b > =A0Creation Time : Wed Mar 25 21:04:08 2009 > =A0 =A0 Raid Level : raid6 > =A0Used Dev Size : 1465137408 (1397.26 GiB 1500.30 GB) > =A0 =A0 Array Size : 5860549632 (5589.06 GiB 6001.20 GB) > =A0 Raid Devices : 6 > =A0Total Devices : 4 > Preferred Minor : 0 > > =A0 =A0Update Time : Sun Jul 12 11:31:47 2009 > =A0 =A0 =A0 =A0 =A0State : clean > =A0Active Devices : 4 > Working Devices : 4 > =A0Failed Devices : 2 > =A0Spare Devices : 0 > =A0 =A0 =A0 Checksum : a59452db - correct > =A0 =A0 =A0 =A0 Events : 580158 > > =A0 =A0 Chunk Size : 64K > > =A0 =A0 =A0Number =A0 Major =A0 Minor =A0 RaidDevice State > this =A0 =A0 2 =A0 =A0 =A0 8 =A0 =A0 =A0 32 =A0 =A0 =A0 =A02 =A0 =A0 = =A0active sync =A0 /dev/sdc > > =A0 0 =A0 =A0 0 =A0 =A0 =A0 8 =A0 =A0 =A0 =A00 =A0 =A0 =A0 =A00 =A0 =A0= =A0active sync =A0 /dev/sda > =A0 1 =A0 =A0 1 =A0 =A0 =A0 0 =A0 =A0 =A0 =A00 =A0 =A0 =A0 =A01 =A0 =A0= =A0faulty removed > =A0 2 =A0 =A0 2 =A0 =A0 =A0 8 =A0 =A0 =A0 32 =A0 =A0 =A0 =A02 =A0 =A0= =A0active sync =A0 /dev/sdc > =A0 3 =A0 =A0 3 =A0 =A0 =A0 8 =A0 =A0 =A0 48 =A0 =A0 =A0 =A03 =A0 =A0= =A0active sync =A0 /dev/sdd > =A0 4 =A0 =A0 4 =A0 =A0 =A0 0 =A0 =A0 =A0 =A00 =A0 =A0 =A0 =A04 =A0 =A0= =A0faulty removed > =A0 5 =A0 =A0 5 =A0 =A0 =A0 8 =A0 =A0 =A0 96 =A0 =A0 =A0 =A05 =A0 =A0= =A0active sync > /dev/sdd: > =A0 =A0 =A0 =A0 =A0Magic : a92b4efc > =A0 =A0 =A0 =A0Version : 00.90.00 > =A0 =A0 =A0 =A0 =A0 UUID : 8d0cf436:3fc2d2ef:93d71b24:b036cc6b > =A0Creation Time : Wed Mar 25 21:04:08 2009 > =A0 =A0 Raid Level : raid6 > =A0Used Dev Size : 1465137408 (1397.26 GiB 1500.30 GB) > =A0 =A0 Array Size : 5860549632 (5589.06 GiB 6001.20 GB) > =A0 Raid Devices : 6 > =A0Total Devices : 4 > Preferred Minor : 0 > > =A0 =A0Update Time : Sun Jul 12 11:31:47 2009 > =A0 =A0 =A0 =A0 =A0State : clean > =A0Active Devices : 4 > Working Devices : 4 > =A0Failed Devices : 2 > =A0Spare Devices : 0 > =A0 =A0 =A0 Checksum : a59452ed - correct > =A0 =A0 =A0 =A0 Events : 580158 > > =A0 =A0 Chunk Size : 64K > > =A0 =A0 =A0Number =A0 Major =A0 Minor =A0 RaidDevice State > this =A0 =A0 3 =A0 =A0 =A0 8 =A0 =A0 =A0 48 =A0 =A0 =A0 =A03 =A0 =A0 = =A0active sync =A0 /dev/sdd > > =A0 0 =A0 =A0 0 =A0 =A0 =A0 8 =A0 =A0 =A0 =A00 =A0 =A0 =A0 =A00 =A0 =A0= =A0active sync =A0 /dev/sda > =A0 1 =A0 =A0 1 =A0 =A0 =A0 0 =A0 =A0 =A0 =A00 =A0 =A0 =A0 =A01 =A0 =A0= =A0faulty removed > =A0 2 =A0 =A0 2 =A0 =A0 =A0 8 =A0 =A0 =A0 32 =A0 =A0 =A0 =A02 =A0 =A0= =A0active sync =A0 /dev/sdc > =A0 3 =A0 =A0 3 =A0 =A0 =A0 8 =A0 =A0 =A0 48 =A0 =A0 =A0 =A03 =A0 =A0= =A0active sync =A0 /dev/sdd > =A0 4 =A0 =A0 4 =A0 =A0 =A0 0 =A0 =A0 =A0 =A00 =A0 =A0 =A0 =A04 =A0 =A0= =A0faulty removed > =A0 5 =A0 =A0 5 =A0 =A0 =A0 8 =A0 =A0 =A0 96 =A0 =A0 =A0 =A05 =A0 =A0= =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 =A0http://vger.kernel.org/majordomo-info.html > --=20 Carl K -- 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