The Drobo systems for Macintosh are some of the worst network drive enclosures you can buy. The look great, but function horribly. I own a Drobo FS unit, slapped four 3TB drives, booted up great, but every single time we tried to back up to it, it would randomly dismount the drive and corrupt the TimeMachine backup.
After 1.5 years of fighting this thing, and having their technical support blame our network wiring, REALLY? We finally pulled the drives out of the enclosure, and installed them inside the Mac Pros and let TimeMachine function from there, OR, get this for the network speed horse crap, installed one drive in an old G5 stuck in the network room right next to the dysfunctional Drobo FS unit, and had our brand new iMacs TimeMachine to it perfectly! So much for the bag of lies and excuses from Drobo.
If you're in the market for a network drive unit AVOID Drobo system. All JUNK!
Oh, and Drobo, if you want this review removed, give me my $700 back.