I still don’t really understand the whole adding drives idea. Right now I have Two 1TB drives inside my drobo. So do I select 2TB as the volume size? The thing I don’t understand is when you add more drives it still says the volume size is 2TB. Sry I’m such a noob! haha
hi, is it a drobo version 1 you have? (4-slots)
ive got 2 of those, (a veersion 1 with usb on theback, and a v2 with usb and firewire on the back)
it depends on what windows you have, and how far you’re planning ahead 
at the moment if you have 2 drives you are essentially mirroring the data (to to protect against 1 drive loss since they are both the same size) and have about 900GB of free (usable) space (eg just under half your total of 2TB) = just under 1tb.
If i understand you correctlly, you are just starting to use the drobo and are at the stage where it says to you want 2tb volume size, 4tb, 8tb 16tb ?
if so, i selected 2TB max size per volume, because i wanted the extra compatibility for my win xp machine, and also in case i take it a friends house in case of emergencies etc. Basically, the drobo will create new volumes for you whenever your total available space goes beyond the max size you specified for each volume.
eg, i started with 2 drives (1tb each), = 2tb total drobo capacity = (call it 1tb useable)
(my drobo drive letter showed up in windows as a 2tb max volume)
i added a 3rd 1tb drive = 3tb total capacity = 2tb usable (your largest drive size is deducted from total and used for protection, as a generic rule of thumb.
now i recently added a 4th (1tb drive) = 4tb approx = 3tb usable…
it was at THIS point that drobo made me a 2nd volume of t2b max, with new drive letter.
(if you click my name you can see my post and thread all about this too)
for me, having a drive letter per 2tb volume isnt a problem, as i prefer the compatibility for now,
however since i have 2 drobos (1 backs onto the other for saftey and different location etc), that means that more of my drive letters will get used up, but thats ok for now.
hope this helps a bit, and if you need more info, just ask and others can help too.
(im just spreading the info that people here kindly gave me, especially the docchris via pms and emails too) from last year
im a resident dj LOL and chris is like the resident doctor LOL 
Thanks for that info. I’m starting to understand the way drobo works a little better now. I have the Drobo 2nd Generation. I have 2 drives inside it (two 1TB drives). And yes, I was at the part where it was asking me to select 1TB, 2TB,4TB etc. I’m guessing I’ll do the same thing you did and select 2TB. I’m also going to partition 640GB to use for time machine (I’m a Mac user). But you’re saying whenever the volume is full, Drobo will automatically create another volume, right?
Thanks for the help!
ahh im only a pc user here, so not too sure for macs, but as far as i know, when you add more capacity eg say 4 1tb drives, it should create (or prompt you with a create option) for the new volume.
(i dont think it will make you new volumes when full… because you would need to add more drives to it first etc)
if youre not in a mad rush, then you can (full edit) this post to add “mac info needed” in the title and a mac guy or someone from data robotics like jennifer can help etc.
Alrighty. Thank so much for the help though. I assume its the same for OS X in terms of Drobo prompting me to create a new drive. Thanks!