Comments on: How-to Recover a RAID array after having Zero-ized Superblocks

By: 16aR

16aR — Thu, 05 Jan 2012 10:25:05 +0000

Thanks for this post, I’ve zeroed my superblock to shrink my RAID-1 array in 2 steps. 1 hard drive after the other.
After a reboot in rescue mode, I couldn’t assemble the array. But creating with –create made it perfect Now it is synchronizing

By: Recover mdadm raid1 data after recreate new array over old

Recover mdadm raid1 data after recreate new array over old — Tue, 13 Dec 2011 16:12:20 +0000

[...] and other info about old md1 array. How can I recover data from old md1 array now? This post: http://kevin.deldycke.com/2007/03/ho…d-superblocks/ claims that if you recreate your original RAID correctly, that the content will not be destroyed. [...]

By: Mike

Mike — Mon, 05 Dec 2011 18:32:44 +0000

Thanks for posting your notes. I found my Fedora 16 x86_64 system unresponsive this morning and had to hard boot it.

During bootup dracut reported that /dev/md1 couldn’t be found.

Boot into rescue and the auto discovery process for Linux partitions couldn’t locate the RAID 5 with it’s Logical Volumes, either.

mdadm --create /dev/md1 --verbose --level=5 --raid-devices=3 /dev/sda1 /dev/sdb1 /dev/sdc1

This found that each of the devices were “part of a raid array” I answered yes to the Continue creating array after which cat /proc/mdstat showed my raid5 array in recovery.

Whoop.

This has happened before on this system, usually over a weekend where the desktop environment sits idle for a couple of days. I suspect some kind of power saving is kicking in on the Fedora 16 desktop. Perhaps it’s trying to sleep the hard disks and somethings getting mucked.

I also noticed I had CStates enabled in the bios, disabling that for future testing.

Thanks again for posting your notes.

By: Arden

Arden — Sat, 30 Jul 2011 00:09:15 +0000

have zeroed superblocks, rebuilt 4 2tb raid 5 twice now, replacing different 2tb drives in different orders (twice) both times once superblocks have been zero’d (which is interesting as original superblocks would be recognized briefly if each ‘missing’ superblock 2tb drive was hot unplugged; then plugged – superblock would show perfect ‘clean’ md info!) but they have been zero’ed twice now; first time out of order of original layout (by mistake) and second time zero’d and rebuilt in orderd as remembered. No avail.

No recognized fs before array rebuild, or after. all drives have always been stated as ‘clean’ even before superblocks have been zero’d.

Any ideas would be great. approx 5tb and 20years of data lost at moment. Thank you for great help so far!

By: [ubuntu] RAID5 Re-Creating MD0 | Coders & Admins

[ubuntu] RAID5 Re-Creating MD0 | Coders & Admins — Thu, 28 Jul 2011 23:52:13 +0000

[...] I came across this site: http://kevin.deldycke.com/2007/03/ho…d-superblocks/ [...]

By: AJ

AJ — Fri, 01 Jul 2011 15:28:29 +0000

Hi there,

Thank you for posting this information. We have had a distantly related problem that this post may have resolved.

We’ve been trying to recover a s/ware raid-5 array from a QNAP 409P NAS where the superblocks of sufficient member drives to render the array inactive were corrupted during a power fault.

We had tried -everything- to get the raid to assemble in a separate system with no success before coming across this page. Having decided that we were unlikely to recover the array, we thought we’d try deliberately zeroing the superblocks for all the member drives and then seeing if re-creating as you describe above would get us back online. The array is resyncing at the moment Hopefully the filesystem in it will be intact.

Many thanks!

- AJ

By: Anonymous

Anonymous — Fri, 10 Jun 2011 13:59:27 +0000

thanks for saving 4.5TB…

By: Mo Firouz

Mo Firouz — Fri, 06 May 2011 00:32:13 +0000

Hello. I have the same problem described by @error and @Gary Dale. However since I actually posted all the codes and etc in ubuntuforums, I was wondering if you were kind enough to have a look at this and tell me if there is anyway that I could mount a newly created md0 without needing to reformat it?

Here is the link:
http://ubuntuforums.org/showthread.php?p=10775382#post10775382

Thank you so much,
Mo

By: mark

mark — Sat, 23 Apr 2011 09:51:58 +0000

this is my current super-block can some one help me with the order to create it in is from /dev/sd[bcdefghi]1 but if failed during an reshape from 6-8 drives

/dev/sdf:

          Magic : a92b4efc
        Version : 0.91.00
           UUID : 01986f9c:c5d44da8:5df300a1:eb89baa4
  Creation Time : Thu Oct 22 18:25:01 2009
     Raid Level : raid5
  Used Dev Size : 976751872 (931.50 GiB 1000.19 GB)
     Array Size : 5860511232 (5589.02 GiB 6001.16 GB)
   Raid Devices : 7
  Total Devices : 7
Preferred Minor : 0

  Reshape pos'n : 1664256 (1625.52 MiB 1704.20 MB)
  Delta Devices : 1 (6->7)

    Update Time : Sat Jan 30 19:30:41 2010
          State : active
 Active Devices : 7
Working Devices : 7
 Failed Devices : 0
  Spare Devices : 0
       Checksum : 8accf9eb - correct
         Events : 219187

         Layout : left-symmetric
     Chunk Size : 128K

      Number   Major   Minor   RaidDevice State
this     6       8      128        6      active sync   /dev/sdi

   0     0       8       33        0      active sync   /dev/sdc1
   1     1       8       49        1      active sync   /dev/sdd1
   2     2       8       65        2      active sync   /dev/sde1
   3     3       8       81        3      active sync
   4     4       8       97        4      active sync   /dev/sdg1
   5     5       8      113        5      active sync   /dev/sdh1
   6     6       8      128        6      active sync   /dev/sdi

By: mdadm software Raid

mdadm software Raid — Sun, 14 Nov 2010 03:22:16 +0000

[...] superblock, etc. I find a website that seems to have the same problem as mine. I think it was http://kevin.deldycke.com/2007/03/ho…d-superblocks/ . I rebuild my raid. Now for some reason I was expect to see my raid alive with my data. [...]