Recover accidentially formatted disc

[frank77]

I recently upgraded from my old Netgear NAS to a DYI Unraid server by transferring data and discs on-by-one (1 cache, 1 2TB parity and three 2TB array discs). 

 

Last task was to upgrade disc 2 from an intermediate 1TB to a 2TB. The disc got included overnight, but way too early on a Sunday morning, Unraid stated that the disc could not be mounted and should be formatted. In a glimpse of early morning negligance i pressed format, thinking this would just re-initiate the inclusion of the disc and the data would still be on the parity disc. 

 

...Apparantly this is not how it works, and the data is now lost. - as it was the last disc in the process, the data is no longer on the old NAS either. 

 

I immediately entered the maintanace mode and XFS repair using this guide, but no luck https://lime-technology.com/wiki/Check_Disk_Filesystems. (the filesystem was xfs both before and after)

 

I have tried several recovery software, but as it was part of a RAID, I have not succeded yet. 

 

Any suggestion or lessons learned would be HIGHLY appreciated 

 

 

[trurl]

Sounds like you have already tried everything I would have suggested. Maybe someone else will have something.

 

As for a lesson, the meaning of the word "format" is often misunderstood. Many seem to think it is just some generic "get this disk ready to use". Format actually means "write an empty filesystem to this disk". And that is what it has always meant in every operating system you have ever used.

 

Like all write operations in the parity array, parity is updated and agrees that the filesystem is empty.

[trurl]

One more lesson. You should always keep backups of any important, irreplaceable files. Parity is no substitute for backups.

 

And another. Always ask here first if you are uncertain.

[JorgeB]

This has helped other users in similar situations before:

 

http://www.ufsexplorer.com/

[trurl]

18 minutes ago, frank77 said:

I have tried several recovery software, but as it was part of a RAID, I have not succeded yet.

Don't give up. Many people have been able to recover files from formatted disks so let others comment.

 

You seem to have some fundamental misconceptions about unRAID though. It is NOT RAID. Each disk is an independent filesystem. Since this is true, you might be able to put the disk in another system and run recovery software. But it will have to be the right software on the right system. I'll let others comment on that since I don't have direct experience. It might help if you could give us more details about how you have tried to recover the data.

 

22 minutes ago, frank77 said:

the data would still be on the parity disc.

None of your data is ever on the parity disc. It obviously doesn't have the capacity for all of the data from all of the disks. Parity plus all of the other disks are required to rebuild a missing or disabled disk. The parity calculation needs the parity bits as well as the bits from all the other disks to calculate the data from a missing disk. Here is a wiki about how parity works. It isn't complicated. Many things about unRAID make more sense if you understand parity.

 

https://lime-technology.com/wiki/UnRAID_6/Overview#Parity-Protected_Array

 

[frank77]

It was definitely a moment of weakness,  no doubt. Next step was to setup the dropbox for the key data... lessons learned on priorities

 

Two things that I feel is not fully tested: Once the XFS_repair has been executed, the guide states that you should restart the array with the Maintenance mode check box unchecked and that's it? Are there no intermediate steps or something to read form the log? Unraid would not even allow me to mount the drive at all.  

Second, I find it particular that the recovery software (Active@ partition recovery in this case) can't find any files on a detailed file-signature scan. I will be able to recover some from the Netgear HDDs using this method, but the difference strikes me.