NAS540: Volume down, repairing failed, how to restore data?

ksr7

At this part of the quest, I really think not.

Don't know why, I was able to see data from the Nas Manager, suddendly I was not.

So I can assume I have no disk containing an original raid header.

How can I check it?

Mijzelf

How can I check it?

Not. The header looks valid for a NAS disk, except for the timestamps. If you don't know if the timestamps could be valid, there is no way to check for validity.

And that means that you can't know for sure which disk is missing.

ksr7

So, what can I do to recover back data?

Mijzelf

I see no simpler way than trying to mount them all 24 permutations.

ksr7

Maybe I got something, on this combination C / A / B / D

Nas said is possible to repair the volume ( even if I can't ), I was confident to reach data, but again nothing appens.

I was going to change configuration, but when I give the command "mdadm --stop /dev/md2" it responds with this : 

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

What now?

Mijzelf

Well, are you sure it isn't mounted? Have a look

cat /proc/mounts

ksr7

~ # cat /proc/mounts

rootfs / rootfs rw 0 0

/proc /proc proc rw,relatime 0 0

/sys /sys sysfs rw,relatime 0 0

none /proc/bus/usb usbfs rw,relatime 0 0

devpts /dev/pts devpts rw,relatime,mode=600 0 0

ubi7:ubi_rootfs2 /firmware/mnt/nand ubifs ro,relatime 0 0

/dev/md0 /firmware/mnt/sysdisk ext4 ro,relatime,user_xattr,barrier=1,data=ordered 0 0

/dev/loop0 /ram_bin ext2 ro,relatime,user_xattr,barrier=1 0 0

/dev/loop0 /usr ext2 ro,relatime,user_xattr,barrier=1 0 0

/dev/loop0 /lib/security ext2 ro,relatime,user_xattr,barrier=1 0 0

/dev/loop0 /lib/modules ext2 ro,relatime,user_xattr,barrier=1 0 0

/dev/loop0 /lib/locale ext2 ro,relatime,user_xattr,barrier=1 0 0

/dev/ram0 /tmp/tmpfs tmpfs rw,relatime,size=5120k 0 0

/dev/ram0 /usr/local/etc tmpfs rw,relatime,size=5120k 0 0

ubi3:ubi_config /etc/zyxel ubifs rw,relatime 0 0

configfs /sys/kernel/config configfs rw,relatime 0 0

Mijzelf

Apparently not. Well, something is keeping the md array occupied. Probably e2fsck. Have a look:

lsof | grep /dev/md2

ksr7

It shows nothing

Mijzelf

And are you sure you still can't stop md2? How about mounting? If mounting fails, what is the output of

e2fsck -n /dev/md2