Recovering a deleted Share

Thanks StephenB.

The share is the folder

And the cake is a lie.

extundelete might work, though I am not certain how to install it on your NAS.

Unfortunately I was not able to install it on the ReadyNas Duo v2. It requires dependencies that have no equivalent on the NAS' OS.
I managed to install TestDisk smoothly, but I wasn't able to undelete any file. I started to scan partitions of the disk (even through USB under Windows) for isolated blocks, which takes too long (I quit at 1797853/3876585471 progress, i.e. 00%).

So because of the slowness and limitations of the Duo OS, I moved to a real machine, running Ubuntu. I managed to access the disk's partitions in various ways and I learned lots of things. Here are my conlcusions:

• 0- System
  Immediately extract disk from bay #2 when you did a foolish thing. The less time you let to the RAID 1 sync, the most chances you'll have to get your data back.
  Move to a more powerful and flexible system to make tests and recovery. You may need to install a large number of apps, libs etc. to make it work.


• 1- TestDisk
  TestDisk can show what kind of partitions table your disk is using, and the nature of each partition, which may be useful. To do it, I just let it starting a Quick Scan. Then I stop it to change type. By default, the type of the scanned partition and its table of partitions are selected. Just note it. In my case, since I didn't change the defaults of the Duo it detected that the partition table is a GPT, and partitions are linux md 1.x RAID. Even if the file system itself is ext4, I understand that I do need to know that it is a linux RAID partition to be able to mount it and browse files.


• 2- mdadm
  mdadm is a tool that enables you to create / mount RAID file systems. I used it to mount the /dev/sdb3 partition containing my almost 2 TB of data. It was a success, though I didn't know what to do with that. I finally umounted it and jumped to step #3.


• 3- extundelete
  extundelete seems to be the ideal tool for the job. Unfortunately, I was not able to make it work since my partition is a linux RAID which seems to be prior to the ext4 file system behind. extundelete works with ext, ext2, ext3 and ext4 file systems exclusively at this time.


• 4- PhotoRec
  PhotoRec is definitely the tool I should have used first. It seems to be based on TestDisk (same interface and vocabulary...) but it just worked for me. Select the type of files you want to recover and just push play. Hours later you'll get 1.5 TB of data recovered (if nothing happened to the data meanwhile, which depends on the time you take to extract the disk from the bay). In my case, I only selected JPG files I lost (whatever are you files' extention, jpeg, jpg of JPG, it looks for the file header itself). It took 4h but I think it may not take much longer for a full recovery, since it browses all disk's blocks anyway. Side effect: filenames are lost (and forget about any form of data structure: folders are gone too, music is over :x ).


• 5- Backup
  Ok. I now understand that RAID 1 is not about backup. I'm ordering a CrashPlan solution right now...

Hope this help and that the level of verbosity is more interesting than annoying.

Tim

PS: Here is a good way to start with mdadm, and here a good way to stop using it (not so easy)!