Thread (7 messages) 7 messages, 4 authors, 2011-11-09

Re: Raid Problem - Unknown File System Type

From: Robin Hill <hidden>
Date: 2011-11-09 16:39:33

On Wed Nov 09, 2011 at 11:12:59AM -0500, William Colls wrote:
Environment

Kubuntu Linux 10.04.3 LTS
mdadm 2.6.7.1-1ubuntu15

I have two identical disks that were in a raid configuration in another 
machine (also running 10.04). I removed them from the old machine, 
mounted them in a new machine, booted up, and at a terminal prompt as 
root issued

mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sdb /dev/sdc
You should have just assembled them. You've now created a new array
instead of just assembling the old one.
The configuration in the old machine was raid 1.

I checked the contents of /proc/mdstat and it confirmed that md0 was 
indeed running, with 2 devices, as expected. But it also said it was 
resyncing the disks, which I didn't expect.

When the reync completed, I was unable to mount /dev/md0p1. Specifying 
-t ext3 in the mount command gives the error message "wrong fs, bad 
option, bad superblock on /dev/md0p1". Trying mount with no -t gives the 
error "unknown file type linux_raid_member". Looking at the disks with 
Gparted, confims that the system sees the disks, but the filesystem 
shows as unknown.
It would look like the old array was either created with an older mdadm
version (with different defaults) or used some non-default parameter
values.
quoted hunk ↗ jump to hunk
The output from mdamd --detail /dev/sdb

/dev/sdb:
           Magic : a92b4efc
         Version : 00.90.00
            UUID : 1443e74d:f63f16ab:d527ef8c:7225e0b0
   Creation Time : Tue Nov  8 13:14:48 2011
      Raid Level : raid1
   Used Dev Size : 732574464 (698.64 GiB 750.16 GB)
      Array Size : 732574464 (698.64 GiB 750.16 GB)
    Raid Devices : 2
   Total Devices : 2
Preferred Minor : 0

     Update Time : Tue Nov  8 16:05:42 2011
           State : clean
  Active Devices : 2
Working Devices : 2
  Failed Devices : 0
   Spare Devices : 0
        Checksum : c4195c85 - correct
          Events : 34


       Number   Major   Minor   RaidDevice State
this     0       8       16        0      active sync   /dev/sdb

    0     0       8       16        0      active sync   /dev/sdb
    1     1       8       32        1      active sync   /dev/sdc
--- end of output
Output from mdadm --examine /dev/sdc

/dev/sdc:
           Magic : a92b4efc
         Version : 00.90.00
            UUID : 1443e74d:f63f16ab:d527ef8c:7225e0b0
   Creation Time : Tue Nov  8 13:14:48 2011
      Raid Level : raid1
   Used Dev Size : 732574464 (698.64 GiB 750.16 GB)
      Array Size : 732574464 (698.64 GiB 750.16 GB)
    Raid Devices : 2
   Total Devices : 2
Preferred Minor : 0

     Update Time : Tue Nov  8 16:05:42 2011
           State : clean
  Active Devices : 2
Working Devices : 2
  Failed Devices : 0
   Spare Devices : 0
        Checksum : c4195c97 - correct
          Events : 34


       Number   Major   Minor   RaidDevice State
this     1       8       32        1      active sync   /dev/sdc

    0     0       8       16        0      active sync   /dev/sdb
    1     1       8       32        1      active sync   /dev/sdc

---- end of output

So - am I truly up the creek without a paddle? Is there any way to 
recover this array? I have backups of most of it, but it will take a 
while to find and restore. And for sure something will be lost.
Certainly most of the data should be there still. I don't suppose you
have a copy of the mdadm --examine output from the old system at all?

Cheers,
    Robin
-- 
     ___        
    ( ' }     |       Robin Hill        [off-list ref] |
   / / )      | Little Jim says ....                            |
  // !!       |      "He fallen in de water !!"                 |

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