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Re: Recovering from Debian Wheezy RAID-1



On 22/12/15 04:44 PM, Narunas Krasauskas wrote:
I have this HDD (WD3200BPVT) which used to be part of the RAID-1 array which has been created with Debian (Wheezy) installer, then AES encrypted, then split into LVM volumes.


    Personalities : [raid1]
    md1 : active raid1 sda2[0] sdb2[1]
          311462720 blocks super 1.2 [2/2] [UU]
    md0 : active raid1 sda1[0] sdb1[1]
          975296 blocks super 1.2 [2/2] [UU]



- sdb1 (1GB real size) here is a member of the system boot partition raid (md0) - sdb2 (~300 GB) was dedicated to everything else, hence encrypted, split into LVM volumes (md1).

Currently I'm on Archlinux, having one of the RAID-1 array disks connected via USB adapter.

    # uname -a
    Linux agn-arch 4.2.5-1-ARCH #1 SMP PREEMPT Tue Oct 27 08:13:28 CET
    2015 x86_64 GNU/Linux



My first problem is that Debian installer somehow shuffled partition table in the way, that my current system cannot recognize correct partition sizes. Here I find 2.3 TB partition on the 320 GB HDD. How or why I'm hoping you debian users can tell me.

    # fdisk -l /dev/sdb
    Disk /dev/sdb: 298.1 GiB, 320072933376 bytes, 78142806 sectors
    Units: sectors of 1 * 4096 = 4096 bytes
    Sector size (logical/physical): 4096 bytes / 4096 bytes
    I/O size (minimum/optimal): 4096 bytes / 4096 bytes
    Disklabel type: dos
    Disk identifier: 0x0009577b


    Device     Boot Start       End   Sectors  Size Id Type
    /dev/sdb1  * 2048   1953791   1951744  7.5G fd Linux raid autodetect
    /dev/sdb2 1953792 625141759 623187968  2.3T fd Linux raid autodetect


Nevertheless it seems that kernel sees more or less correct partition sizes:

    # cat /proc/partitions | grep sdb
       8       16  312571224 sdb
       8       17  7806976 sdb1
       8       18  304756056 sdb2



My second problem - mdadm cannot detect md super block:

    # mdadm -V
    mdadm - v3.3.4 - 3rd August 2015


    # for v in 0 0.90 1 1.0 1.1 1.2 default ddf imsm; do mdadm -E -e
    $v /dev/sdb; done
    mdadm: No super block found on /dev/sdb (Expected magic a92b4efc,
    got 00000000)
    mdadm: No super block found on /dev/sdb (Expected magic a92b4efc,
    got 00000000)
    mdadm: No super block found on /dev/sdb (Expected magic a92b4efc,
    got 00000000)
    mdadm: No super block found on /dev/sdb (Expected magic a92b4efc,
    got 009063eb)
    mdadm: No super block found on /dev/sdb (Expected magic a92b4efc,
    got 7208ec45)
    mdadm: No super block found on /dev/sdb (Expected magic a92b4efc,
    got 00000000)
    mdadm: No super block found on /dev/sdb (Expected magic a92b4efc,
    got 009063eb)
    mdadm: No super block found on /dev/sdb (Expected magic a92b4efc,
    got 7208ec45)
    mdadm: No super block found on /dev/sdb (Expected magic a92b4efc,
    got 7208ec45)
    mdadm: Cannot read anchor block on /dev/sdb: Invalid argument
    mdadm: /dev/sdb is not attached to Intel(R) RAID controller.
    mdadm: Cannot read anchor block on /dev/sdb: Invalid argument
    mdadm: Failed to load all information sections on /dev/sdb

    # for v in 0 0.90 1 1.0 1.1 1.2 default ddf imsm; do mdadm -E -e
    $v /dev/sdb1; done
    mdadm: No super block found on /dev/sdb1 (Expected magic a92b4efc,
    got a2a14843)
    mdadm: No super block found on /dev/sdb1 (Expected magic a92b4efc,
    got a2a14843)
    mdadm: No super block found on /dev/sdb1 (Expected magic a92b4efc,
    got 6cc72f52)
    mdadm: No super block found on /dev/sdb1 (Expected magic a92b4efc,
    got 00000000)
    mdadm: No super block found on /dev/sdb1 (Expected magic a92b4efc,
    got 00000000)
    mdadm: No super block found on /dev/sdb1 (Expected magic a92b4efc,
    got 6cc72f52)
    mdadm: No super block found on /dev/sdb1 (Expected magic a92b4efc,
    got 00000000)
    mdadm: No super block found on /dev/sdb1 (Expected magic a92b4efc,
    got 00000000)
    mdadm: No super block found on /dev/sdb1 (Expected magic a92b4efc,
    got 00000000)

    # for v in 0 0.90 1 1.0 1.1 1.2 default ddf imsm; do mdadm -E -e
    $v /dev/sdb2; done
    mdadm: No super block found on /dev/sdb2 (Expected magic a92b4efc,
    got 00000000)
    mdadm: No super block found on /dev/sdb2 (Expected magic a92b4efc,
    got 00000000)
    mdadm: No super block found on /dev/sdb2 (Expected magic a92b4efc,
    got 00000000)
    mdadm: No super block found on /dev/sdb2 (Expected magic a92b4efc,
    got 6b3a399e)
    mdadm: No super block found on /dev/sdb2 (Expected magic a92b4efc,
    got b3afa73a)
    mdadm: No super block found on /dev/sdb2 (Expected magic a92b4efc,
    got 00000000)
    mdadm: No super block found on /dev/sdb2 (Expected magic a92b4efc,
    got 6b3a399e)
    mdadm: No super block found on /dev/sdb2 (Expected magic a92b4efc,
    got b3afa73a)
    mdadm: No super block found on /dev/sdb2 (Expected magic a92b4efc,
    got b3afa73a)


Funny enough metadata is still here, because I had to reassemble my old box to recover my files. That's how things look like from the booted Wheezy:

    /dev/sdb1:
              Magic : a92b4efc
            Version : 1.2
        Feature Map : 0x0
         Array UUID : 2bb13374:a6ecf587:e36a71f4:1f5423f8
               Name : debox:0  (local to host debox)
      Creation Time : Sat May 31 20:25:34 2014
         Raid Level : raid1
       Raid Devices : 2

     Avail Dev Size : 1950720 (952.66 MiB 998.77 MB)
         Array Size : 975296 (952.60 MiB 998.70 MB)
      Used Dev Size : 1950592 (952.60 MiB 998.70 MB)
        Data Offset : 1024 sectors
       Super Offset : 8 sectors
              State : clean
        Device UUID : 9391880b:43da3522:9c4df953:a3b8bedc

        Update Time : Tue Dec 22 20:14:47 2015
           Checksum : 9f42638 - correct
             Events : 191


       Device Role : Active device 1
       Array State : AA ('A' == active, '.' == missing)


    /dev/sdb2:
              Magic : a92b4efc
            Version : 1.2
        Feature Map : 0x0
         Array UUID : 27fd9812:9836ddfb:9268168c:24f45e49
               Name : debox:1  (local to host debox)
      Creation Time : Sat May 31 20:25:44 2014
         Raid Level : raid1
       Raid Devices : 2

     Avail Dev Size : 622925824 (297.03 GiB 318.94 GB)
         Array Size : 311462720 (297.03 GiB 318.94 GB)
      Used Dev Size : 622925440 (297.03 GiB 318.94 GB)
        Data Offset : 262144 sectors
       Super Offset : 8 sectors
              State : clean
        Device UUID : c6d0863a:41e5758f:5ff58502:ff90e968

        Update Time : Tue Dec 22 20:28:10 2015
           Checksum : 2622cbac - correct
             Events : 533


       Device Role : Active device 1
       Array State : AA ('A' == active, '.' == missing)



Luckily this time I have had a healthy RAID-1 array with no failing HDD, next time it may be mission critical data recovery...

I would really appreciate if community could explain where did I fail, why I couldn't get my data back, what does Debian installer does so special that other systems can't recover data, etc...

Thank you.

Regards

Narūnas

I don't see Debian doing anything wrong. fdisk showing a 2.3T partition I am assuming comes on your Arch Linux disk and is a result of it using the wrong block size. I'm not sure if this is due to the use of a USB adapter.

mdadm -E /dev/sdb should fail because /dev/sdb is not a RAID device. mdadm -E /dev/sdb1 should work.


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