OSX Lion and Drobo dashboard show different capacities

I am a first time user and have acquired the Drobo 4 bay firewire storage device. I have a few questions that I am hoping someone can help me with.

  1. OSX Lion shows 2.2 TB of space on the device even before I installed any drives in the unit. I found that strange for obvious reasons. OSX Lion even wanted to format the (empty) Drobo!

  2. After I installed the drives, installed Drobo dashboard etc., OSX Lion still shows the device at 2.2 TB capacity when the dashboard shows 937GB. Why is this?

its called thin provisioning

you can FORMAT the device to any size - you could even make it be 16TB

but you can never put more data on it than you have in terms of disks, which is what dashboard shows - your actual space