Drobo Series 3 Speed Sucks:

Update: Read more on my Drobo Saga above.

Series 3 Drobo, 4 drives: 3/2/3/4TB (7.2TB net storage)

Firmware 4.1.4

Tested with BlackMagic Disk Speed Test on Mac Pro 8 core 2009 flashed to 2010. Newertech USB 3 PCIe card.

Tests:

25% free (75% used)

About 30Mbyte/second if I'm lucky. 

I think this is due to the very large number of files on the unit due to a Time Machine volume and a data drive and somehow the 4TB drive addition seemed to slow it down but note that I have had no errors in weeks on it, and the 4TB drive has gotten moved to my Mac Pro internally with no isses and no SMART trips via SMARTReporter.