From what I have read you can use the globalSAN initiator. However I have not tried this. What I can say is that the iSCSI initiator they bundle their mac version of the drobo dashboard with is a pain - except if you manually force your mac to boot in 32 bit mode.
I own a drobopro, had it plugged in straight to my mac via ethernet, but moved to FW800 as that has proven to be very reliable - not so much the ethernet connection - unmounting drobos via editing video footage is really not something you want. the globalSAN ISCSI could be better and not suffer from the same problems, worth a try!
Oh and if you are using the drobopro to edit HD footage or large amounts of data, make sure it stays below 60% full, as from then on it begins to slow down, up until 90 percent where it slows to a crawl. Just a word of advice from personal experience.
iSCSI has been a big bag of hurt with my Mac Pro (1st gen) and Drobo Pro. Randomly locks (hard locks) my server at random. Prior to installing Drobo Dashboard and this unit my machine had been rock solid.
I’ve spent 5 days trying to get this to work properly.
Going to try the Global San initiator and possibly ATTO initiator instead.
It’s amazing that there is no fix for this 64 bit issue.