Re: Data recovery from linear array (Intel SS4000-E)

[Johannes Moos <jmoos@gmx.de>]

Hi Phil,

I recreated the Array and it started.

> As you can see, the partition table corresponds to the size of the 
> combined devices. Metadata type 0.90 is at the end of each member, so 
> the first sector of loop0 will become the first sector of md0. 

Right, /dev/md0 now looks exactly the same as /dev/loop0:

root@ThinkPad /media/Backup/NAS # fdisk -l /dev/md0
Disk /dev/md0: 1638.7 GB, 1638744850432 bytes
255 heads, 63 sectors/track, 199232 cylinders, total 3200673536 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

     Device Boot      Start         End      Blocks   Id  System
/dev/md0p1               1       16064        8032   77  Unknown
/dev/md0p2           16065  3200673535  1600328735+  88  Linux plaintext

>>  From what I read in a forum it's possible to mount the XFS partition 
>> with an offset, in my case that would be 00ae0000 (last line in 
>> hexdump).
> Shouldn't be necessary.  I expect your LV w/ XFS to show up properly.

Nothing happened, so I tried as described in the forum post I mentioned 
(about a pretty much identical NAS and so LVM):

root@ThinkPad /media/Backup/NAS # hexdump -C /dev/md0 | head -n 150 | 
grep XFSB
00ae0000  58 46 53 42 00 00 10 00  00 00 00 00 00 04 00 00  
|XFSB............|

Offset for XFS-Partition is 00ae0000, that's 11403264 in decimal, so I 
tried (read only):

root@ThinkPad /media/Backup/NAS # losetup -r -o 11403264 /dev/loop4 
/dev/md0

and then I got:

root@ThinkPad /media/Backup/NAS # disktype /dev/loop4
--- /dev/loop4
Block device, size 1.490 TiB (1638733447168 bytes)
XFS file system, version 4
   Volume name ""
   UUID 705BF11E-8F69-1CDA-8727-00004868BBE3 (DCE, v1)
   Volume size 1 GiB (1073741824 bytes, 262144 blocks of 4 KiB)

Small progress, but volume size only 1 GiB?
I didn't ran xfs_check or xfs_repair so far because there's probably a 
better way to do it :)

Best regards,
Johannes Moos