Hey guys,

 

I had the unthinkable happen recently and had 2 drives fail due to an electrical surge. Unfortunately I only have a single parity drive (+4 storage drives).

 

I have sent the drives to a data recovery centre and they are able to recover one of the drives, the other drive is unfortunately not able to be recovered. They have said that it is possible to do a block level clone of the "good" drive onto a new drive. 

 

Would it be possible to use this cloned drive back in the array to emulate/rebuild the drive that they cannot fix?

 

Essentially I would need to update the unraid config to think that the new drive is the old drive. If this is possible how can I do it?

 

Thanks.

 

 

Edited March 26, 20197 yr by Pumped

Yes, you'd need to do a new config and use the invalid slot command, do you know if it's a data drive? Also what Unraid release are you running.

It is a data drive. I am running 6.6.7.

 

Attached a screenshot of the drives.

 

Disk 3 is the drive that can't be fixed, and disk 4 is the one they are attempting to clone.

Edited March 26, 20197 yr by Pumped

15 minutes ago, Pumped said:

Disk 3 is the drive that can't be fixed

Assuming disk2 is the one missing, when you get the cloned disk4 do this:

 

-Tools -> New Config -> Retain current configuration: All -> Apply
-Assign any missing disk(s) including cloned disk4 and a new disk2
-Important - After checking the assignments leave the browser on that page, the "Main" page.

-Open an SSH session/use the console and type (don't copy/paste directly from the forum, as sometimes it can insert extra characters):

mdcmd set invalidslot 2 29

-Back on the GUI and without refreshing the page, just start the array, do not check the "parity is already valid" box, disk2 will start rebuilding, disk should mount immediately but if it's unmountable don't format, wait for the rebuild to finish and then run a filesystem check

34 minutes ago, johnnie.black said:

Assuming disk2 is the one missing

  

Sorry. Yes, disk 2 is the one that will be missing.

 

Thanks for your help. I will post results back here when I get the drive returned.

Ok got the drives back today. I have done the disk assignments and double checked them.

 

I see this message near my parity drive 'All existing data on this device will be OVERWRITTEN when array is Started'

 

And Starting the array without "parity is already valid" presents the warning "Parity disk(s) content will be overwritten"

Is this correct? If I am to recover the content of disk 2 don't I require the parity to remain in tact? I haven't proceeded past this dialog yet.

Edited April 1, 20197 yr by Pumped

8 minutes ago, Pumped said:

Is this correct?

Yes, the GUI doesn't account for the invalidslot command.

 

Just make sure you follow the instructions carefully, especially the part about not refreshing the GUI after typing the command.

Ok, Disk 2 and 4 are "Unmountable" but a data rebuild and parity sync is running.

Disk 4 is showing "Unmountable: Unsupported partition layout"

 

Is this an issue?

3 minutes ago, Pumped said:

Is this an issue?

Yes, it means it's not a 100% clone of the original, but it might still be possible to access it later.

 

Disk2 being unmountable is also not a good sign, but wait for the rebuild to finish, you can grab and post current diags so we can see why disk2 isn't mounting.

Damn. That doesn't sound good. Attached diags.

 

tower-diagnostics-20190401-0335.zip

There is a xfs filesystem on disk2, that's good, if everything else is well it should be fixable when the rebuild finishes, as for disk4 maybe they only cloned the partition, not the mbr, and that would cause that error, but if it's only that it's easily fixable.

 

For now wait for the rebuild finish and then check filesystem on disk2.

I had the data recovery place give me a copy of the available data on a secondary drive so I have already been able to retrieve the disk4 data. Hoping the clone will help repair disk2.

 

Waiting patiently for the rebuild (~20 hours remaining). Either way, very much appreciate your help @johnnie.black. You're a legend.

Ok, good news. Rebuild completed overnight and was sucessful. Everything is green.

 

I ran xfs_repair -v /dev/md2 -L on disk2 and the disk mounted   🙌

I can also see all the data correctly on disk 2 so it looks like it worked.

 

Running the same filesystem check on disk 4 did not yield any changes and I am still seeing the "Unmountable: Unsupported partition layout"

 

tower-diagnostics-20190401-1329.zip

10 hours ago, Pumped said:

Running the same filesystem check on disk 4 did not yield any changes and I am still seeing the "Unmountable: Unsupported partition layout"

That's expected, if it's just a partition problem rebuilding the disk will correct that, and since you already have the data from disk4 no risk anyway:

stop array

unassign disk 4

start array

check if the emulated disk mounts, if yes rebuild on top, if not run a filesystem check on it.

The emulated disk mounted so I assigned the same disk and it is rebuilding as we speak.

 

Thanks again @johnnie.black. You've saved me from the wrath of my wife 😂🤣