I’ve already submitted a ticket to Drobo Support, but thought it’d be a good idea to share here, in case someone else has experienced this:
My drive is not mounting… I’ve tried using different cables (USB3 and TB), different computers, upgraded the Dashboard software, shutdown and removed and reseat all drives…
When I turn it on:
- Front power light glows yellow, all drive lights turn yellow, all bottom lights light blue and rightmost (xfer) light turns green.
- Front power light turns off, xfer light turns off.
- All blue lights turn off. Yellow drive lights remain on.
- All drive lights flash once, remain yellow and front power light turns yellow.
- Then the blue lights begin flashing in an inward flowing pattern. Yellow drive lights turn off. Front power light alternates between yellow and green.
- Blue lights stop. Front power light turns green.
Drive will remain in this state for a while and then repeat this pattern, over and over.
MacMini i7 running OS X 10.8.5
Dashboard 2.6.4 
Not sure what firmware is on the drive.
I’ve got 5 Seagate 3TB drives and the memory card that slips in the bottom of the drive.