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Old 04-15-2011, 07:27 AM   #1
Registered: Jul 2010
Distribution: openSUSE 11.4
Posts: 33

Rep: Reputation: Disabled
Moving software RAID0 from openSUSE to Slackware


I have a software RAID0 consisting of 2 disks on a machine running openSUSE. RAID was created with help of YAST's Partitioner feature. Now I'm planning to replace Suse with Slackware, so I've run a simulation in virtualbox, creating RAID exactly the same way as it was created on "real" machine, installing Slackware and trying to reassemble it with mdadm.

This is where trouble and confusion begin.
root@slackraid:~# mdadm --assemble /dev/md0 /dev/sdb1 /dev/sdc1
mdadm: no recogniseable superblock on /dev/sdb1
mdadm: /dev/sdb1 has no superblock - assembly aborted
Then I do a little examination of devices involved:
root@slackraid:~# mdadm --query /dev/sdb1
/dev/sdb1: is an md device which is not active

root@slackraid:~# mdadm --query /dev/sdc1
/dev/sdc1: is not an md array
/dev/sdc1: device 1 in 2 device unknown raid0 array.  Use mdadm --examine for more detail.
Why would the same command give different results for identical drives?
root@slackraid:~# mdadm --examine /dev/sdb1
mdadm: No md superblock detected on /dev/sdb1.

root@slackraid:~# mdadm --examine /dev/sdc1
          Magic : a92b4efc
        Version : 1.0
    Feature Map : 0x0
     Array UUID : 763b9c53:1adbffe0:29d4db6f:19756de5
           Name : HW-OPENSUSE:0
  Creation Time : Thu Apr 14 22:16:48 2011
     Raid Level : raid0
   Raid Devices : 2

 Avail Dev Size : 2121712 (1036.17 MiB 1086.32 MB)
  Used Dev Size : 0
   Super Offset : 2121712 sectors
          State : clean
    Device UUID : b90dbad2:1c87bd82:2d71a991:b8366fb8

    Update Time : Thu Apr 14 22:16:48 2011
       Checksum : 4af21230 - correct
         Events : 0

     Chunk Size : 128K

    Array Slot : 1 (0, 1)
   Array State : uU
How come /dev/sdb1 is an inactive md device, but has no superblock, and /dev/sdc1 has correct superblock, but not is an md device?

Can someone explain this to me? Thanks in advance.
Old 04-18-2011, 01:07 PM   #2
Registered: Aug 2010
Location: Beaverton, Oregon, USA
Distribution: Pfsense, Ubuntu, Centos, Fedora, Redhat, Scientfic, MacOS
Posts: 76

Rep: Reputation: 19

My thought is to check if the superblock on /dev/sdb1 got corrupted. I believe under ext[234] filesystems the superblock is copied to redundant blocks on the disk. I don't know if it's the same with a software raid array.



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