Moving disks between NASes

There is a frequent question I’d like to address: is it safe to move disk packs between identical NASes?

The full version may well go like this

Last night my Ready NAS (RND4000) stopped working. It looks like a fault in the power supply…I would like to recover some…files.

One option I see is a friend of mine who owns the same system. Is it an option to shut down his NAS, remove/replace the installed disks with the disks from my NAS and copy the data? Or are any obstacles in the way?

All in all, it should work. Possible obstacles include

  1. Different NAS models. Obviously, the NASes must be of the same vendor, same product line, and in most cases models must be fully identical.
  2. Different firmware. Preferably, both NASes should use the same firmware version. However, once the unit fails, there is no way to determine exactly which firmware it was running at the time of crash. In this situation, the recipient unit is better be patched to the latest firmware. The latest firmware will typically accept disk packs created by older versions.
  3. Damage to the disks, either physical or logical. When the power supply blows, it may take the NAS with it; also the disks may or may not be damaged by electrical transients. If this happens, the replacement NAS is not going to work, obviously.

If you think none of this applies to your situation, you may give it a go.