I recently updated from 2TB drives to 10TB drives in my RN204. I went one by one and let the new array build-out. This was in RAID10 btw.
If there was something that I removed from the 10TB drives that still exists on the 2TB drives, is there a way to recover that data easily? If so, what would the best way be to approach that?
Re: Getting data back off older drives, swapping, etc
I'd say that this will not be a very easy task - if at all possible. The problem is that every disk you pulled out and replaced caused the remaining drives to sync with the new drive.
*IF*, and that's a large if, data structure remains the same on the 2TB drives as it syncs in the 10TB AND nothing changed on the volume during the syncs.. Perhaps it's possible to force sync everything together. Mdadm for sure will not let you do that by default as the event counts will be far off.
You're probably better off looking for backups elsewhere or seeking data recovery help rather than experimenting on your own. The thing about forcing the mdadm array together is that it may make recovery less likely.
Re: Getting data back off older drives, swapping, etc
Thanks for the info! The data itself should still exist on all the drives, it's just that they won't recognize one another when put in the array together? I actually tried this and got some message about the disks or volume being inactive, which seems to correspond with what you were saying. Will I be able to boot up and see the data with a single of the 2tb drives in the NAS? Perhaps the next best thing I can do is attempt to mount one of the drives via btrfs and retrieve the data from there?
Re: Getting data back off older drives, swapping, etc
@jplee3 wrote: ...it's just that they won't recognize one another when put in the array together?
Basically that. The drive replacements cause the RAID to be reshaped (blocks of data get shuffled around). So when you are done the four 2TB drives aren't a coherent RAID array any more.
@jplee3 wrote: ...it's just that they won't recognize one another when put in the array together?
Basically that. The drive replacements cause the RAID to be reshaped (blocks of data get shuffled around). So when you are done the four 2TB drives aren't a coherent RAID array any more.
Make sense... am I still able to retrieve data off the individual drives at least? I'm messing around with mdadm and btrfs but not quite sure what to do... I think I may have already messed one of the drives up going a bit too far with that.
Make sense... am I still able to retrieve data off the individual drives at least? I'm messing around with mdadm and btrfs but not quite sure what to do... I think I may have already messed one of the drives up going a bit too far with that.
Well you can read the raw data blocks on each disk. But the files and metadata are spread across the disks - so you probably won't be able to recover many files.
Probably your best shot is to try ReclaiMe. You can download it, and see what files it can find. Then buy it if it finds the ones you need. That is expensive though.
Running mdadm and btrfs on your own is likely to do more damage. If you want to explore that path, clone the drives and play with the clones.
Make sense... am I still able to retrieve data off the individual drives at least? I'm messing around with mdadm and btrfs but not quite sure what to do... I think I may have already messed one of the drives up going a bit too far with that.
Well you can read the raw data blocks on each disk. But the files and metadata are spread across the disks - so you probably won't be able to recover many files.
Probably your best shot is to try ReclaiMe. You can download it, and see what files it can find. Then buy it if it finds the ones you need. That is expensive though.
Running mdadm and btrfs on your own is likely to do more damage. If you want to explore that path, clone the drives and play with the clones.
What would happen if I were to pop back in one or two of the 2TB drives to the NAS? Would the data just get overwritten on those anyway?
Seems like I'd have to attempt rebuilding the entire array with all four 2TB disks connected otherwise?
Re: Getting data back off older drives, swapping, etc
I'm not sure how many ways you need to be told this. No, it won't work. The drives that make up your RAID array cannot be accessed individually. The data is distributed across them all, even for an individual file (unless it's only 1 sector long). And even for the tiniest of files, the directory structure is spread throughout. There is no way at all to ever reclaim files from just one drive. At a minimum, you need all but one simultaneously, and all of them together will give you the best chance at recovery using a method capable of doing that..
