NAS326 problem - part 2 - help is needed - Volume is down

Janikovo

Hello all,
and especially @Mijzelf

You probably know my problem with one faulty disk on NAS326 (linear, jbod).
Look here: https://homeforum.zyxel.com/discussion/3827/nas326-problem/p1

Problem is how to "assemble" NAS volume (or array back) without losing data.

So, I managed with ddrescue copied 99.999% of that faulty disk to the news HDD same size.

Installed the new disk to NAS, but the situation is as follows:



















What should I do now ?
Please an advice
and Thanks.

#NAS_June_2020

Mijzelf

The array is assembled, but it fails to mount. So try running fsck:

e2fsck /dev/md2

Janikovo

@Mijzelf

~ # e2fsck /dev/md2

e2fsck 1.42.12 (29-Aug-2014)

/dev/md2 is in use.

e2fsck: Cannot continue, aborting.

Thats all.

Janikovo

OK,

i tried add -n to e2fsck

and it show this:

~ # e2fsck -n /dev/md2

e2fsck 1.42.12 (29-Aug-2014)

Warning!  /dev/md2 is in use.

ext2fs_open2: Bad magic number in super-block

e2fsck: Superblock invalid, trying backup blocks...

e2fsck: Bad magic number in super-block while trying to open /dev/md2

The superblock could not be read or does not describe a valid ext2/ext3/ext4

filesystem.  If the device is valid and it really contains an ext2/ext3/ext4

filesystem (and not swap or ufs or something else), then the superblock

is corrupt, and you might try running e2fsck with an alternate superblock:

    e2fsck -b 8193 <device>

 or

    e2fsck -b 32768 <device>

btw:
mdadm --stop /dev/md2:

~ # mdadm --stop /dev/md2

mdadm: Cannot get exclusive access to /dev/md2:Perhaps a running process, mounted filesystem or active volume group?

So, I cant stop md2

How could I assemble volume (array) without losing data ?

Mijzelf

So, I cant stop md2

You can't stop md2, because it's busy. md2 is not mounted, so there must be something else. I should have looked further, apart from md2 there is also a dm-1 in /proc/partitions, which is slightly smaller than md2. So inside your raid array there is a 'logical volume', and that logical volume is the one containing the file system.

So try

e2fsck /dev/dm-1

I am not sure if that dm-1 devicenode is inside /dev/. If /dev/dm-1 cannot be found, try

find /dev/ grep dm

to find the path to the devicenode.