Thread (8 messages) 8 messages, 2 authors, 2014-12-04

Re: mdadm creates corrupt superblock

From: NeilBrown <hidden>
Date: 2014-11-19 21:47:09 

On Wed, 19 Nov 2014 10:55:05 +0100 Hans Kraus [off-list ref] wrote:

Hi,

I think I found the problem. 'badblocks' reports sector 64 of the HD as
errornous. But the HD neither reports a read error nor remaps that
sector.

Is it possible to parametrize mdadm that it doesn't use that sector?
I'm surprised that md is using sector 64.
The superblock is at sectors 8,9
The bitmap at 16..24, or something like that
The data is at 262144 onwards.

But that are offsets in sdb1, maybe the '64' is a sector number in 'sdb'.

Where does 'sdb1' start in 'sdb'??

NeilBrown


Regards, Hans

Am 29.10.2014 22:11, schrieb Hans Kraus:
quoted
Hi Neil,

many thanks for your response. I rebooted the machine and got new drive
assignments. The drive in question is now sdc1. mdadm gave an error with
the dump, results below (nothing to report by dmesg) [by the way, I
wasn'nt even able to create an array on that drive with
'mdadm --create --level=1 -n 2 /dev/sdc1 missing', same error(s)]:
-------------------------------------------------------------------------
root@nashorn:~# mdadm -E /dev/sdb1
/dev/sdb1:
           Magic : a92b4efc
         Version : 1.2
     Feature Map : 0x1
      Array UUID : e7caa5d1:b33fd2a5:7782fb0c:9d8d9d5b
            Name : nashorn:126  (local to host nashorn)
   Creation Time : Mon Oct 27 15:58:38 2014
      Raid Level : raid1
    Raid Devices : 2

  Avail Dev Size : 1953260976 (931.39 GiB 1000.07 GB)
      Array Size : 976630488 (931.39 GiB 1000.07 GB)
     Data Offset : 262144 sectors
    Super Offset : 8 sectors
    Unused Space : before=262056 sectors, after=0 sectors
           State : clean
     Device UUID : f7a91c46:e4cda0c0:1b770fd7:876634f8

Internal Bitmap : 8 sectors from superblock
     Update Time : Wed Oct 29 18:42:16 2014
   Bad Block Log : 512 entries available at offset 72 sectors
        Checksum : 939b22d1 - correct
          Events : 3325


    Device Role : Active device 0
    Array State : AA ('A' == active, '.' == missing, 'R' == replacing)
root@nashorn:~#
-------------------------------------------------------------------------
root@nashorn:~# mdadm -E /dev/sdh1
/dev/sdh1:
           Magic : a92b4efc
         Version : 1.2
     Feature Map : 0x1
      Array UUID : e7caa5d1:b33fd2a5:7782fb0c:9d8d9d5b
            Name : nashorn:126  (local to host nashorn)
   Creation Time : Mon Oct 27 15:58:38 2014
      Raid Level : raid1
    Raid Devices : 2

  Avail Dev Size : 1953260976 (931.39 GiB 1000.07 GB)
      Array Size : 976630488 (931.39 GiB 1000.07 GB)
     Data Offset : 262144 sectors
    Super Offset : 8 sectors
    Unused Space : before=262046 sectors, after=0 sectors
           State : clean
     Device UUID : 089d1d0e:4d5ca222:dd716acb:0813815c

Internal Bitmap : 8 sectors from superblock
     Update Time : Wed Oct 29 18:42:16 2014
   Bad Block Log : 512 entries available at offset 82 sectors
        Checksum : 16454b96 - correct
          Events : 3325


    Device Role : Active device 1
    Array State : AA ('A' == active, '.' == missing, 'R' == replacing)
root@nashorn:~#
-------------------------------------------------------------------------
root@nashorn:~# mdadm -E /dev/sdc1
/dev/sdc1:
           Magic : a92b4efc
         Version : 1.2
     Feature Map : 0x1
      Array UUID : e7caa5d1:b33fd2a5:7782fb0c:9d8d9d5b
            Name : nashorn:126  (local to host nashorn)
   Creation Time : Mon Oct 27 15:58:38 2014
      Raid Level : raid1
    Raid Devices : 2

  Avail Dev Size : 1953260976 (931.39 GiB 1000.07 GB)
      Array Size : 0
   Used Dev Size : 0
     Data Offset : 262144 sectors
    Super Offset : 8 sectors
    Unused Space : before=262056 sectors, after=1953260976 sectors
           State : clean
     Device UUID : 4d1420c6:79978477:e86412b1:24beebfc

Internal Bitmap : 8 sectors from superblock
     Update Time : Tue Oct 28 11:53:49 2014
   Bad Block Log : 512 entries available at offset 72 sectors
        Checksum : 6f02d040 - expected 891eedff
          Events : 0


    Device Role : spare
    Array State : RR ('A' == active, '.' == missing, 'R' == replacing)
-------------------------------------------------------------------------
root@nashorn:~# mkdir -p /tmp/dump
root@nashorn:~# mdadm --dump /tmp/dump /dev/sdc1
mdadm: Failed to copy metadata from /dev/sdc1 to /tmp/dump/sdc1
-------------------------------------------------------------------------
Kind regards, Hans

Am 28.10.2014 22:00, schrieb NeilBrown:
quoted
On Tue, 28 Oct 2014 19:06:20 +0100 Hans Kraus [off-list ref]
wrote:
quoted
Hi,

I debugged my problem a bit more: it seems that mdadm creates a defect
superblock. That's repeatedly happening, but only for one drive. I
copied zeros to that drive (via ddrescue /dev/zero ...) and the drive
looks OK. The info I got:
and you send me the metadata of all your devices please?

    mkdir /tmp/dump
    mdadm --dump /tmp/dump /dev/sde1
    tar czvf /tmp/dump.tgz /tmp/dump

and then send /tmp/dump.tgz

Thanks.

NeilBrown

=================================================================================================================================================================================================
quoted
root@nashorn:/home/kraush/work/smartctrl# mdadm --zero-superblock
/dev/sde1
mdadm: Unrecognised md component device - /dev/sde1
root@nashorn:/home/kraush/work/smartctrl# mdadm --add /dev/md126
/dev/sde1
mdadm: add new device failed for /dev/sde1 as 4: Invalid argument
root@nashorn:/home/kraush/work/smartctrl# mdadm -E /dev/sde1
/dev/sde1:
            Magic : a92b4efc
          Version : 1.2
      Feature Map : 0x1
       Array UUID : e7caa5d1:b33fd2a5:7782fb0c:9d8d9d5b
             Name : nashorn:126  (local to host nashorn)
    Creation Time : Mon Oct 27 15:58:38 2014
       Raid Level : raid1
     Raid Devices : 2

   Avail Dev Size : 1953260976 (931.39 GiB 1000.07 GB)
       Array Size : 0
    Used Dev Size : 0
      Data Offset : 262144 sectors
     Super Offset : 8 sectors
     Unused Space : before=262056 sectors, after=1953260976 sectors
            State : clean
      Device UUID : 4d1420c6:79978477:e86412b1:24beebfc

Internal Bitmap : 8 sectors from superblock
      Update Time : Tue Oct 28 11:53:49 2014
    Bad Block Log : 512 entries available at offset 72 sectors
         Checksum : 6f02d040 - expected 891eedff
           Events : 0


     Device Role : spare
     Array State : RR ('A' == active, '.' == missing, 'R' == replacing)
root@nashorn:/home/kraush/work/smartctrl#
-----------------------------------------------------------------------------------------------------------

root@nashorn:/home/kraush/work/smartctrl# cat /proc/mdstat
Personalities : [raid1] [raid6] [raid5] [raid4]
md127 : active (auto-read-only) raid6 sda1[0] sdk1[6](S) sdl2[7](S)
sdh1[5] sdg1[4] sdf1[3] sdc1[2] sdb1[1]
        1953017856 blocks super 1.2 level 6, 512k chunk, algorithm 2
[6/6] [UUUUUU]
        bitmap: 0/4 pages [0KB], 65536KB chunk

md10 : active (auto-read-only) raid1 sdi2[0] sdl3[1]
        87833408 blocks super 1.2 [2/2] [UU]
        bitmap: 0/1 pages [0KB], 65536KB chunk

md126 : active raid1 sdd1[3] sdj1[2]
        488254464 blocks super 1.2 [2/2] [UU]
        bitmap: 0/4 pages [0KB], 65536KB chunk

md0 : active raid1 sdl1[4] sdd2[3] sdi1[5]
        156157824 blocks super 1.2 [3/1] [U__]
        [===================>.]  recovery = 95.6% (149290048/156157824)
finish=8.4min speed=13496K/sec
        bitmap: 1/2 pages [4KB], 65536KB chunk

unused devices: <none>
root@nashorn:/home/kraush/work/smartctrl#
-----------------------------------------------------------------------------------------------------------

dmesg:
[33299.387382] md: invalid superblock checksum on sde1
[33299.387385] md: sde1 does not have a valid v1.2 superblock, not
importing!
[33299.387408] md: md_import_device returned -22
root@nashorn:/home/kraush/work/smartctrl#
-----------------------------------------------------------------------------------------------------------

root@nashorn:/home/kraush/work/mdadm# mdadm --version
mdadm - v3.3-161-gfed12d4 - 21st August 2014
=================================================================================================================================================================================================


Kind regards, Hans
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