Multiple volumes - with more than 16 TB


I have one large 16 TB volume on my Drobo Pro and that’s how far it can go in terms of volume size, if I understand correctly.

The other day I was playing around with Dashboard and I was very surprised to find out it would let me add more volumes.

Is this possible at all? How does it do that?

Say I have the one 16TB volume, total storage capacity (real) is 9 TB, free space is currently 1,8 TB. What would happen if I add another volume, say 1 TB in size?


you could have 16 x 16TB volumes - you could still never add more than 9tb of data to drobo in total.

you’ve already got one volume thats bigger than the disks on it - its not difficult to imagine a second

ok, but how dows it distribute the total storage available to the different volumes? equally?

That is something you would have to do manually. You can either divide the data equally between the volumes or you can have 8TB in 1 volume and 500 gb in a 2nd volume and 500 gb in a 3rd volume. You will just never be able to exceed 9TB total between all the volumes.

Exactly - the free space is shared between the volumes - think of it as a “pool” of free space that each of the volumes can take from as and when they need it - so when drobo’s central pool of free space is exhausted you just cant add any more files to any of your volumes (even if they look to the OS like they have available free space)

think of the volumes as large empty rooms - but anything you need to put in those rooms you have to gift wrap first! (the gift wrap is your available free space)

you only have a certain amount of gift wrapping - so you can put your gift wrapped packages in which ever room you like - but when you run out of gift wrapping - you can’t add any more to your big empty rooms (even though they appear to have lots of free space in them)

likewise you can move your files/gift wrapped packages between your big empty rooms without affecting the amount of gift wrapping (free space) left over

(can you tell - i like my new analogy!)

if you need more storage you can buy more/larger hard disks - thats like buying more gift wrapping - and then you can put more things in your big empty rooms - and the rooms still look the same size

(your 16 x 16tb volumes - but you now have the ability to put more in them due to more physical storage)

All right, I think I got it, thanks a lot guys.

So basically it’s safe to add more volumes, even if you don’t have the actual free space, because Drobo manages this all (I think the term for this would be thin provisioning, right?)?


your current volume is already thin provisioned, having additional thin provisioned volumes will make no difference