Drobo with 2 partitions (one for time machine), unknown free space?

I have a Drobo v2 firewire and created 2 partitions on it, one large and one small to use it for Time Machine. I followed the instructions on Drobo’s website for doing so, pasted below so I’m not accused of not following the directions:

"To create a partition on your Drobo storage device for use with Time Machine, please follow these steps:

Warning: Reformatting a Drobo device with Drobo Dashboard erases all data. Be sure you either save your data to another location before following this procedure or you perform this procedure on empty drives.

Using Drobo Dashboard, format your Drobo storage device with HFS+ and select a volume size (for example, 8TB).
Open Disk Utility and select the Drobo volume – but do not actually format the Drobo volume.
Select the “Partition” tab and change the “Volume Scheme” to 2 Partitions.
Select the top partition and enter a name and a size value.
Ensure that the Format: is Mac OS Extended (Journaled).
Select the bottom partition and enter a name.
Ensure that the Format: is Mac OS Extended (Journaled).
Click the “Options…” button and ensure that the “GUID Partition Table” option is selected.
Click the “Apply” button and click the “Partition” button on the “Partition Disk” dialog.
The two volumes should format and complete in a few minutes."

Time machine seems to work fine using this method. My only problem is that I have no idea how much free space I have on either of the partitions. I raised this issue quite a while ago and was told with the software updates that Drobo Dashboard would be able to tell you this information. Well, alas, the only thing that the dashboard reports after this update came is that it’s a partitioned volume with multiple partitions, and 380.28 GB free space (see image). My question is how is the 380 GB divided up? I have no way of knowing how much free space is on either partition.

Can anyone tell me how I can decipher how much free space is on Partition A and Partition B??? See the screenshot below, this is what I see. The drobo volumes are shown on the desktop named “Drobo” and “Time Machine” Please help. Thanks.