How many drives can you swap?

Hi Everyone,
I have just got my Drobo FS and looking for a couple of pointers.

I put in my 4 existing drives (1x2TB and 3x1TB) with the idea of swapping the 2TB drive (going from 5400rpm to 7200) and also put in a 2nd one to increase the capacity.

Do I need to put in the extra one first, let it rebuild and then swap the other one and rebuild again?


Can I just pull out the 2TB and put both of the new ones in at the same time, therefore only doing one rebuild?

Also, is it literally just a case of pulling out the drive whilst it is on?


The only thing I can tell you for sure is a bad idea is to pull out drives during a rebuild. Not sure about adding drives during a rebuild, though.

Thanks Ricardo, I guessed that probably wouldn’t be a great idea ;-), just wasnt sure whether I could cut down the rebuild times.

Guess I’ll stick with the safe option, put the new drive in and wait for the rebuild before swapping the other one.


You can add as many new drives as you want at once. You can only exchange one at a time, existing for replacement.

Thanks Kaelaria, any ideas on doing both at the same time (replacing one and inserting a new one)?

I never had to do it, but would not be concerned if I did.

The first one you put in after removing a drive it will treat as a replacement and start the relayout. When you put in another it will simply start spreading data to it also. The danger is when removing multiple drives not adding.

This might be a good time for someone to explain how the internal disk manager has the concept of “critical disks” which are disks that, if removed, would cause the array to fail.

An example of a non-critical disk would be the replacement in a degraded array that’s still rebuilding. Another example would be a recently added disk which has only redundant data on it.