Help needed - RAID5 recovery from Power-fail
I wonder if you could help a Raid Newbie with a problem I had a power fail, and now I can't access my RAID array. It has been working fine for months until I lost power... Being a fool, I don't have a full backup, so I really need to get this data back. I run FC4 (64bit). I have an array of two disks /dev/sda1 and /dev/sdb1 as a raid5 array /dev/md0 on top of which I run lvm and mount the whole lot as /home. My intention was always to add another disk to this array, and I purchased one yesterday. When I boot, I get: md0 is not clean Cannot start dirty degraded array failed to run raid set md0 I can provide the following extra information: # cat /proc/mdstat Personalities : [raid5] unused devices: # mdadm --query /dev/md0 /dev/md0: is an md device which is not active # mdadm --query /dev/md0 /dev/md0: is an md device which is not active /dev/md0: is too small to be an md component. # mdadm --query /dev/sda1 /dev/sda1: is not an md array /dev/sda1: device 0 in 2 device undetected raid5 md0. Use mdadm --examine for more detail. #mdadm --query /dev/sdb1 /dev/sdb1: is not an md array /dev/sdb1: device 1 in 2 device undetected raid5 md0. Use mdadm --examine for more detail. # mdadm --examine /dev/md0 mdadm: /dev/md0 is too small for md # mdadm --examine /dev/sda1 /dev/sda1: Magic : a92b4efc Version : 00.90.02 UUID : c57d50aa:1b3bcabd:ab04d342:6049b3f1 Creation Time : Thu Dec 15 15:29:36 2005 Raid Level : raid5 Raid Devices : 2 Total Devices : 2 Preferred Minor : 0 Update Time : Tue Mar 21 06:25:52 2006 State : active Active Devices : 1 Working Devices : 1 Failed Devices : 2 Spare Devices : 0 Checksum : 2ba99f09 - correct Events : 0.1498318 Layout : left-symmetric Chunk Size : 128K Number Major Minor RaidDevice State this 0 810 active sync /dev/sda1 0 0 810 active sync /dev/sda1 1 1 001 faulty removed #mdadm --examine /dev/sdb1 /dev/sdb1: Magic : a92b4efc Version : 00.90.02 UUID : c57d50aa:1b3bcabd:ab04d342:6049b3f1 Creation Time : Thu Dec 15 15:29:36 2005 Raid Level : raid5 Raid Devices : 2 Total Devices : 2 Preferred Minor : 0 Update Time : Tue Mar 21 06:23:57 2006 State : active Active Devices : 2 Working Devices : 2 Failed Devices : 0 Spare Devices : 0 Checksum : 2ba99e95 - correct Events : 0.1498307 Layout : left-symmetric Chunk Size : 128K Number Major Minor RaidDevice State this 1 8 171 active sync /dev/sdb1 0 0 810 active sync /dev/sda1 1 1 8 171 active sync /dev/sdb1 It looks to me like there is no hardware problem, but maybe I am wrong. I cannot find any file /etc/mdadm.confnor /etc/raidtab. How would you suggest I proceed? I'm wary of doing anything (assemble, build, create) until I am sure it won't reset everything. Many Thanks Nigel - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Help needed - RAID5 recovery from Power-fail
On Monday April 3, [EMAIL PROTECTED] wrote: > I wonder if you could help a Raid Newbie with a problem > > I had a power fail, and now I can't access my RAID array. It has been > working fine for months until I lost power... Being a fool, I don't have > a full backup, so I really need to get this data back. > > I run FC4 (64bit). > I have an array of two disks /dev/sda1 and /dev/sdb1 as a raid5 array > /dev/md0 on top of which I run lvm and mount the whole lot as /home. My > intention was always to add another disk to this array, and I purchased > one yesterday. 2 devices in a raid5?? Doesn't seem a lot of point it being raid5 rather than raid1. > > When I boot, I get: > > md0 is not clean > Cannot start dirty degraded array > failed to run raid set md0 This tells use that the array is degraded. A dirty degraded array can have undetectable data corruption. That is why it won't start it for you. However with only two devices, data corruption from this cause isn't actually possible. The kernel parameter md_mod.start_dirty_degraded=1 will bypass this message and start the array anyway. Alternately: mdadm -A --force /dev/md0 /dev/sd[ab]1 > > # mdadm --examine /dev/sda1 > /dev/sda1: > Magic : a92b4efc > Version : 00.90.02 >UUID : c57d50aa:1b3bcabd:ab04d342:6049b3f1 > Creation Time : Thu Dec 15 15:29:36 2005 > Raid Level : raid5 >Raid Devices : 2 > Total Devices : 2 > Preferred Minor : 0 > > Update Time : Tue Mar 21 06:25:52 2006 > State : active > Active Devices : 1 So at 06:25:52, there was only one working devices, while... > > #mdadm --examine /dev/sdb1 > /dev/sdb1: > Magic : a92b4efc > Version : 00.90.02 >UUID : c57d50aa:1b3bcabd:ab04d342:6049b3f1 > Creation Time : Thu Dec 15 15:29:36 2005 > Raid Level : raid5 >Raid Devices : 2 > Total Devices : 2 > Preferred Minor : 0 > > Update Time : Tue Mar 21 06:23:57 2006 > State : active > Active Devices : 2 at 06:23:57 there were two. It looks like you lost a drive a while ago. Did you notice? Anyway, the 'mdadm' command I gave above should get the array working again for you. Then you might want to mdadm /dev/md0 -a /dev/sdb1 is you trust /dev/sdb NeilBrown - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Help needed - RAID5 recovery from Power-fail
Neil Brown wrote: >On Monday April 3, [EMAIL PROTECTED] wrote: > > >>I wonder if you could help a Raid Newbie with a problem >> >> >It looks like you lost a drive a while ago. Did you notice? > This is not unusual - raid just keeps on going if a disk fails. When things are working again you really should read up on "mdadm -F" - it runs as a daemon and sends you mail if any raid events occur. See if FC4 has a script that automatically runs it - you may need to tweak some config parameters somewhere (I use Debian so I'm not much help). David - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Help needed - RAID5 recovery from Power-fail
Neil Brown wrote: > 2 devices in a raid5?? Doesn't seem a lot of point it being raid5 > rather than raid1. Wouldn't a 2-dev raid5 imply a striped block mirror (i.e faster) rather than a raid1 duplicate block mirror (i.e. slower) ? Thanks! -- Al - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Help needed - RAID5 recovery from Power-fail - SOLVED
Thanks for all the help. I am now up and running again and have been stable for over a day. I will now install my new drive and add it to give me an array of three drives. I'll also learn more about Raid, mdadm and smartd so that I am better prepared next time. Thanks again Nigel Neil Brown wrote: > On Monday April 3, [EMAIL PROTECTED] wrote: > >> I wonder if you could help a Raid Newbie with a problem >> >> I had a power fail, and now I can't access my RAID array. It has been >> working fine for months until I lost power... Being a fool, I don't have >> a full backup, so I really need to get this data back. >> >> I run FC4 (64bit). >> I have an array of two disks /dev/sda1 and /dev/sdb1 as a raid5 array >> /dev/md0 on top of which I run lvm and mount the whole lot as /home. My >> intention was always to add another disk to this array, and I purchased >> one yesterday. >> > > 2 devices in a raid5?? Doesn't seem a lot of point it being raid5 > rather than raid1. > > >> When I boot, I get: >> >> md0 is not clean >> Cannot start dirty degraded array >> failed to run raid set md0 >> > > This tells use that the array is degraded. A dirty degraded array can > have undetectable data corruption. That is why it won't start it for > you. > However with only two devices, data corruption from this cause isn't > actually possible. > > The kernel parameter >md_mod.start_dirty_degraded=1 > will bypass this message and start the array anyway. > > Alternately: > mdadm -A --force /dev/md0 /dev/sd[ab]1 > > >> # mdadm --examine /dev/sda1 >> /dev/sda1: >> Magic : a92b4efc >> Version : 00.90.02 >>UUID : c57d50aa:1b3bcabd:ab04d342:6049b3f1 >> Creation Time : Thu Dec 15 15:29:36 2005 >> Raid Level : raid5 >>Raid Devices : 2 >> Total Devices : 2 >> Preferred Minor : 0 >> >> Update Time : Tue Mar 21 06:25:52 2006 >> State : active >> Active Devices : 1 >> > > So at 06:25:52, there was only one working devices, while... > > > >> #mdadm --examine /dev/sdb1 >> /dev/sdb1: >> Magic : a92b4efc >> Version : 00.90.02 >>UUID : c57d50aa:1b3bcabd:ab04d342:6049b3f1 >> Creation Time : Thu Dec 15 15:29:36 2005 >> Raid Level : raid5 >>Raid Devices : 2 >> Total Devices : 2 >> Preferred Minor : 0 >> >> Update Time : Tue Mar 21 06:23:57 2006 >> State : active >> Active Devices : 2 >> > > at 06:23:57 there were two. > > It looks like you lost a drive a while ago. Did you notice? > > Anyway, the 'mdadm' command I gave above should get the array working > again for you. Then you might want to >mdadm /dev/md0 -a /dev/sdb1 > is you trust /dev/sdb > > NeilBrown > > > - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
