On 11/09/2011 11:39 AM, Robin Hill wrote:

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

quoted

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.

I thought, at the time, that I needed to do the create so that the 
/dev/md0 device would be created properly (new machine had no raid before).

quoted

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

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?

No output from the original setup.

Cheers,
     Robin

-- 
I know you believe that you understand what you think I said, but I am 
not sure that you realize that what you heard was not what I ment.