Data Volume lost after disk replacement on Readynas Pro 6

Ouch.  Normally I'd suggest contacting Netgear support - but of course OS 6 is not supported on the Pro.  Still they might be willing to take a data recovery contract (not sure).

Multiple disk failures do happen, and rebuilding the array when you replace a disk stresses all the others.

BTW (for future reference) it is a very bad idea to run a scrub on a compromised volume.

I have decided to give it go myself.

Read a lot, found that raid/parity setups are not really good solutions anymore in these days where disks are so much larger and so different from those when these systems were created (1995-ish?). Raid 10 seems to be the current preferred setup by professionals. (no complicated expensive parity calculation, disk space is "cheap"). I further found some real good insight on recovery chances: according to one: in 85% of cases it can be solved with software, in 10% it is the circuit board, which you can even hotswap and I have 5 spare.., in 4% it is the heads or the platters, and in 1% it is the motor.

So  I reckon I have a larger than 95% chance to recover my data. Worth a try.

First port of call is to make bit by bit images of the drives so that I don't have to use them for the actualy inspection and recovery of the data. I use the free linux version of r-data to make them, so that I have some idea of the chances for succes before I buy the software. I could also have used ddrescue, both these tools  read the disk sequentially (as an old fashioned record) which is the least demanding for the (now fragile) HDDs.

Bought a esata hot swap cradle, filled the nas pro with 6 new disks (JBOD) and started with r-data to make images. The original disk2 (which triggered the problem) can't be read. That is a candiate for another PCB, and I could eventually replace the heads if necessary.  I am currently imaging nr5, the second one that give up. Apart from a few strange noises in the early stage, the imaging process is proceeding without errors. I think that if this one works and the sixth images fine I should be able to restor the array.

I am not a pro as I stated above, any advice is welcome, to be continued.

Disk 5 and 6 imaged successfully, according to r-Linux.

R-linux can scan the images, I see lots of files but they are all numbered. Hell of a task to open each one and rename.....

So next is trying to recover the array: Downloaded and installed reclaime free raid recovery on a Windows 8.1 laptop and started the raid 5 analysis. Reclaime seems the be very good in finding back the original raid configuration, which can than be used by r-studio to recover the files with original names and file structure.

After I started the raid 5 scan, reclaime quickly found disk two to be empty. This means that the sync process had failed. If the other images are ok than I think this should be enough. Otherwise I might still have to try to recover the original disk2.

The analysis can take a few days, more news if and when.

In the mean time I am setting up an NV+ v1 as dedicated backup machine (boot, check integrity, backup, shutdown).

Does anyone know how to setup an NV+ to JBOD?

Never mind, found it.

Succes! The data is back!

Most discussions I recently read on raid 5 recovery were not very encouraging. And XRaid-2 got even less reactions, let alone positive ones. Not very promising: After I had made the images of the six drives I tried first to repair the faulty disk that started the disaster.  Not immediately succesfull I turned  to software recovery from the images. I started with Reclaime's free raid recovery, but that did not work for me.The raid array was not recognised. During the scans I searched for the raid parameters of a XRaid-2 config. Turns out they do not exist, as it is a dynamic raid setup. Then I found a first digestable insight in nas partitions, with referral to readynas XRaid-2 on Youtube: https://youtu.be/kGvBZdKFdFc. After 20 minutes on btrfs, lvm and dynamic raid arrays, recovering dynamic raid arrays did not sound very promising anymore..

I tried RTT's software, and I contacted a few software vendors, who let me know that as XRaid-2 is a proprietary raid setup they could not detect, analyse or repair it. Encouragement levels dropping ...

I then contacted Reclaime with the question if their "free raid recovery" software could (should be able to) detect and rebuild the XRaid-2 array from a six disk array with one probably missing (the failed sync on disk 2). I got a message back advising me to use "Reclaime File Recovery". This did not immediately work, but it did provide some encouraging results recognising the size of the array and the original number of drives. After a few mails and an update the software recognised all the images and the full original array. Within minutes the original filesystem was available after which I started copying out files to my JBOD NV+. Within three hours I had recoverd all my critical data.

At the moment I am still copying less important files, but I am not entirely sure if I will recover all the data. It might be that I have lost something due to the two drive crashes and subsequent sync and scrub actions. The software is still analysing the disc-images, repiecing files that might have been unreadable due to the disk crashes or deleted due to the failed sync process or disk scrub. I understand that btrfs is good for that, lets see.

Me however, I am amazed, and as you may image very, very happy that I found a solution. One of the things that impressed me is Reclaime's software, their knowledge or raid arrays, HDD drives and Nas system,  and their support: Exemplary. Turns out that the video I found was theirs, and they have a whole library of youtube video's on the subjects, higly recommended.

So, what's next: setup my readynas pro again as a X-Raid2 system? Well.. with solutions from Recliame I might just give it a go again....

But I probaly won't: If I am correct the key reason for Raid was to offer multiple fysical drives as one logical volume, thus offering capacity and speed.  (in 1995, a 1GB HDD became commonplace according to http://www.relativelyinteresting.com/comparing-todays-computers-to-1995s/)  This introduced interdependency between disks that was subsequently adressed with parity or redundancy, or both.

Today's 2TB HDD's are common, fast, and can store so much data that I really wonder if there is a need to offer multiple 2GB drives in a raid/parity setup as one logical drive for a home situation, or a small office. And as we still need to rely on a backups I believe there is a good case for increasing capacity eliminating parity, and reducing dependency between disks, thus avoiding Raid completely: A weekly backup may do, and I will never lose more than the actual disks that fail, if the backup fails too. Much less risk, and what is more, much less hassle, especially in recovery...