On 02/21/2013 12:23 PM, Stone wrote:

i coud try to restore the superblock. the filesystem is ext4....
is this the right way?
mke2fs -n -j /dev/mapper/md2_nas

Partly. (scary) Without the "-n", that will destroy everything!

mke2fs 1.41.14 (22-Dec-2010)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=128 blocks, Stripe width=384 blocks
366288896 inodes, 1465133568 blocks
73256678 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=0
44713 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
        32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632,
2654208,
        4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968,
        102400000, 214990848, 512000000, 550731776, 644972544

But it does give you the locations of the backup superblocks.  Use these
numbers, starting with 32768, as "xxxx" in:

fsck.ext4 -n -b xxxx /dev

Once you give it a superblock that hasn't been corrupted, it should be
able to check the rest of the filesystem.  There will be damage near the
beginning, and probably more damage where you had to put zeros.

If it looks like that, do it again without "-n" to actually fix it.

Phil