Forum Discussion

Aspirant

Sep 29, 2023

Solved

ReadyNAS 516 cannot mount RAID volume

Good afternoon! I am trying to access data on my ReadyNAS 516, using firmware 6.10.8. It has 6 drives of 4TB each, running in a RAID 5 configuration. After a batch of storm-caused power interruptions, disk 1 failed. I replaced it with a similar one, and the system started rebuilding. The morning after, I woke up to see that the system could not mount the RAID volume. RAIDair shows the following:

The admin page shows the following:

The latest log shows the following:

Looking at the logs it seems that volume 1 was resynced, but then there was a fault in disk 6 and as a consequence the RAID volume could not be assembled. I would like to recover the data, but I am not able at this time to spend the cost of Netgear level 3 support. So I tried to ssh from my windows PC, using Putty, reassemble the array using mdadm and then mount the BTRFS volume. However, when I SSH using the admin account and password, I get the message:

Could not chdir to home directory /home/admin: No such file or directory

and the connection is closed.

I would appreciate any help you can provide to me, as DIY is as far as I see the only way to get the data back. I also understand that I should have had a backup, and I had, but I am ashamed to admit that it was not updated, at all.

My bad!!

adomenicus
Oct 03, 2023
Thanks to StephenB I was able to mount the volume using

mdadm --assemble --really-force /dev/md127 /dev/sd[abcdef]3

and then painfully copy all folders and files onto spare external drives. I say painfully because the NAS was trying to rebuild the RAID drive while doing so, and performance was a dismay. While I am sure there is a way to safely prevent that, I did not try as data recovery was priority #1.

So now I can say that all data has been recovered, and I have ordered the disks to start brand new and build a new RAID drive to dump the restored data into. I have also ordered a large drive to make a regular backup ... just in case.

Thanks to StephenB and the community. You rock!!

3 Replies

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StephenB
Guru - Experienced User
Sep 29, 2023
adomenicus wrote:

when I SSH using the admin account and password, ...

the connection is closed.

You need to log in as root using the NAS admin password.

adomenicus wrote:

Looking at the logs it seems that volume 1 was resynced, but then there was a fault in disk 6 and as a consequence the RAID volume could not be assembled.

I am thinking that the resync might not have been fully completed (perhaps the volume was vertically expanded in the past?). Download the full log zip file, and take a look there.

If you like, I could take a look. If you are interested, put the zip into cloud storage and PM me a download link (using the envelope icon in the upper right of the forum page). Make sure the permissions are set so anyone with the link can download.
- adomenicus
  Aspirant
  Sep 29, 2023
  Thank you so much! Dumb of me I did not realize I had to log in as root. I PMed you the link to the log file. Truly appreciate any help!
- adomenicus
  Aspirant
  Oct 03, 2023
  Thanks to StephenB I was able to mount the volume using
  
  mdadm --assemble --really-force /dev/md127 /dev/sd[abcdef]3
  
  and then painfully copy all folders and files onto spare external drives. I say painfully because the NAS was trying to rebuild the RAID drive while doing so, and performance was a dismay. While I am sure there is a way to safely prevent that, I did not try as data recovery was priority #1.
  
  So now I can say that all data has been recovered, and I have ordered the disks to start brand new and build a new RAID drive to dump the restored data into. I have also ordered a large drive to make a regular backup ... just in case.
  
  Thanks to StephenB and the community. You rock!!