Duplicate Drobo volume


I’ve a 5D with 5 x 6TB WD RED’s installed. This was working fine until I removed a faulty drive. Ran it for a week whilst the faulty drive was replaced under warranty and re-inserted into it. Now I have two Drobo volumes. One is the normal 16TB volume (double redundancy set) and an unformatted 16TB volume. When I open the dashboard it nags me to format it - I’ve not for obvious reasons, not wishing to lose my good volume. I can’t delete/remove it. What did I do wrong and how do I remove it?

Thanks in advance,


Did you previously have 5 x 6tb disks? If so then you would have had two volumes already.
with double redundancy that gives you 18Tb of usable space

or during this replacemenent of a drive - have you increased your capacity? if so then that is what has happened

Since you cant address all 18Tb of that space with your existing 16tb volume, drobo has created a second volume for you.

it is safe to let drobo format it for you

you cannot remove this volume as it is there to allow you to utilise the additional space unaddressable by your 16tb volume.

Hi Docchris,

Thanks for the reply.

Yes I originally had 5 x 6TB drives installed (double redundancy set). Using one “Drobo” volume, I also had a 1TB Timemachine volume too that I forgot to mention. I took one drive out and also unchecked the Double Redundancy check-box. I ran this for a week or so before re-inserting the replaced warranty drive. Now I have two Drobo volumes of the same size 15-16TB and one is now un-formatted and the Timemachine volume using Double Redundancy set.

According to the Drobo capacity calculator with 5 x 6TB drives using Double Redundancy I should have 16.34TB of free space. I’ll check the sizes of my volumes again tonight but either way I have two volumes the same size indicated one formatted in use and the other unformatted which doesn’t add up with double redundancy set. So I’m still reluctant to format the unformatted volume without backing up the 16TB volume first, which is no mean feat.



Checked my volumes last night: Three volumes: -
0 Drobo HFS+ 16TB
2 Drobo Not Formatted 16TB
1 Timemachine Backup 1000GB

So how do I remove volume 2?