Recover data from Unmountable Disk

[Sarthak Varshney]

Hi Guys, looking for an urgent and quick support, on a very tight timeline for project and my data is inaccessible.

 

My Unraid Config is:

 

Processor: AMD Ryzen 3200G

RAM: 16GB

Parity: Segate Enterprise Exos X16 10TB

Data Disk / Disk 1: Segate Enterprise Exos X16 10TB

File System: BTRFS

 

Few days back after cleaning my server, my data disk started giving me knocking or clicking sound. I did a parity check once to ensure all data is secure. Then I got a new 10TB HDD to make a copy of existing data on disk1. I put the new disk in disk2 slot and created some shares post which my new disk gave some errors and I got it replaced. I then did a preclear on the replacement disk and tried to assign it again to disk2 and I don't know what happened the new HDD suddenly vanished.

 

I then restarted my system twice and then I find out that "Unassigned Devices" is listing my new 10TB HDD but my existing Data Drive (Disk 1) was shown as unmountable.

I saved the syslog at this point, and when I tried to access the disk via Ubuntu I got the same error message there

mount: /mnt/disk1: wrong fs type, bad option, bad superblock on /dev/md1, missing codepage or helper program, or other error.

I am unable to access disk1 any how now. The scrub option is unavailable on disk1. 

 

I also tried to replace disk1 with the new disk and then tried to start the array but then Unraid gave the error "Too Many Disks Missing" and I couldn't start the array.

 

So this is what I have now:

 

1) A parity disk which has data in secure form.

2) Data disk (disk 1) which is unmountable.

3) Disk 2 which is always showing missing.

4) New 10TB disk which is precleared.

 

Can anyone please guide me how can I either,

Mount my disk1 and recover data from it? or

Use my parity to recover data on to my new drive?

 

Please help me on an urgent basis, I am stuck between my ongoing project and I've already passed my deadline.

 

Thanks in advance

 

 

syslog [https://pastebin.com/raw/QEmbH9XL]

 

[JorgeB]

Aug 14 16:22:13 SVServer kernel: BTRFS error (device md1): parent transid verify failed on 40517632 wanted 83423 found 83421
Aug 14 16:22:13 SVServer kernel: BTRFS error (device md1): parent transid verify failed on 40517632 wanted 83423 found 83421

 

This error is fatal with btrfs, both metadata copies are on the wrong transition id, this means that the disk lost some writes, i.e., it didn't respect write barriers, it told the OS all writes were done, the btrfs superblock was updated but it turns out not all writes were done, this is usually a controller/disk firmware problem.

 

You can try the first two options here, 1st option is more likely to work if first you update to v6.10.3, still btrfs restore is usually the option with more chances of success for this particular error, if/when the data is recovered the disk will need to be formatted, like mentioned this fs error cannot be fixed, it's fatal.

[Sarthak Varshney]

Hey @JorgeB!

 

Thanks for your quick response, I did try out the option 1 partially but I didn't work. I'll try it out again and the second option too. 

But I'd like you to help me with the disk2 missing option too. As soon as I put my new 10TB disk in disk2 (which is showing disk missing) the parity check starts, and I quickly stop the parity cuz I don't want to mess with disk1 parity data. 

 

So please tell me how to assign / use the new disk so that if either of options work for unmountable disk and am able to read data, I can then quickly start copying the data.

 

Thanks 

[JorgeB]

14 minutes ago, Sarthak Varshney said:

But I'd like you to help me with the disk2 missing option too. As soon as I put my new 10TB disk in disk2 (which is showing disk missing) the parity check starts, and I quickly stop the parity cuz I don't want to mess with disk1 parity data. 

 

Disk2 is disabled, if you add a disk to that slot and start the array Unraid will rebuild disk2, not parity, emulated disk2 is mounting correctly so you can rebuild it at any time, now or after attempting to recover the data from disk1, but don't do both at the same time, both require reading disk1 so performance will be worse.

[JorgeB]

You should also post the complete diagnostics here in the forum, attach them to your next post, just to confirm everything else looks good.

[Sarthak Varshney]

Thanks for the quick response. I'll execute it and get back to you.

[trurl]

4 hours ago, Sarthak Varshney said:

A parity disk which has data in secure form.

parity has none of your data

[Sarthak Varshney]

7 minutes ago, trurl said:

parity has none of your data

 

What I mean is, my parity is valid and I checked it before (when my disk1 was accessible), so I can recover data / rebuild data from parity, that is possible right?

[Kilrah]

A rebuild from parity will restore your drive to exactly the same state it's in now, broken filesystem included.

Parity only protects against outright drive failure, not data corruption.