Drobo and Drobo 1 (8D)

Since my setup I have always had Drobo and Drobo 1 icons on my Mac desktop.
This also shows up as different volume names in my Dashboard.
Both have ~15TB of space. But now Drobo 1 is filled and when I want to add files to Lightroom it says my Drobo is filled when there is still 15 TB of space.
How do I combine Drobo and Drobo 1

When you originally set up your 8D, you may not have been aware of a firmware upgrade which increased the maximum volume on an 8D from 16TB to 128TB. As a result you are experiencing Thin Provisioning, where the Drobo automatically creates additional 16TB volumes as you add or replace/upsize your HDDs.

Here is a link to a similar thread on a 5D3 which explains your options:

Not great options!
Since my Drobo is mainly for LR images, having two 16TB volumes would be cumbersome as you would have to go back and forth in the Library while working on various images depending which volume they were on.
On the other hand downloading all 15TBs of my existing images on to another HD and then back once Drobo is reconfigured would take days and days.
Thanks for your answer.

Have worked on it a bit. Having separate volumes in LR is not an issue. It will read them as two drives and I can split my folders between them without compromising workflow.
So the question I have now is what happens when I add bigger drives? Does a third volume get set up? Can I direct added space to one of the two existing drives?

Your existing drives are the 16TB volumes that Drobo initialised. They cannot be increased in size.
When you add or upsize HDDs which then exceed the capacity of the existing volumes, another 16TB volume (and hence another drive) will be setup for you, and so on.

If you maintain an external back-up regime of your Drobo data as well (I would recommend it if you don’t currently), that backup set will allow you to reset your Drobo completely to a single 128TB volume, and then repopulate with data.

Thanks again.
I do have a second backup off site. Long story but it is on multiple drives for each year.
I just think it will be too time consuming to remove, reformat and replace my existing 16+ TBs of data.
I talked with Drobo today and they had the same rec… But I also played with LR and I am happy to use the individual volumes as designated HDs on LR.
The workflow doesn’t change if I spread my images over the two volumes and can add future ones as needed when I add larger drives to the Drobo, understanding that I would have to go in roughly 16TB increments.
Moving folders in LR is much easier and safer so I don’t have to consider one massive drive.
I tested the second volume today with some small folders and it works fine. Attached is a LR screenshot with the two Drobo volumes (Drobo and Drobo 1). I will move some more files over to the new volume and all future folders will go there until I need a third volume.
I am going to switch to Dual Redundancy so I won’t have a third 16TB volume (I have 48TB total). Down the road I plan on replacing some 4s with 8s.
Drobo was great help today and you have been as well.

Looks like a plan then. Cheers