If I configure my gen 2 Drobo with a volume size of 8 TB will the Drobo create a second 8 TB volume with 10 TB of installed drives. - And what if I only have 8 TB of installed drives?
hi ecamhi, here is a break down for you that might help…
the gen2 will be supporting a single drive redundancy mode, SDR, so with this in mind, the general formula i use is this:
drive 1 + d2 + d3 + d4 = total raw capacity in TB
raw value TB (-x TB for SDR, where x is the TB size of your largest drive) = actual capacity
actual TB (*0.9 for filesystem overheads) = your usable space (approximately)
if your usable space value is less than the size of your max volume size, then you only get the 1 volume, and if its larger than that, then you would get a 2nd volume. (the 2nd volume would also show 8TB of free space to the computer, in your case, but you would need to look at dashboard to see actual used and free space your drobo has overall, so that you dont overfill it)
i wasnt sure what drives and sizes you actually have, but i hope this helps a bit and if you get stuck or want some more info please let us know - and welcome too 
Paul
This answers my question. Thanks.
Eli
ok cool