I’m guessing from the amount of hits on the Drobo article from 2009 that people are still having problems with Drobos rebuilding the array in a decent amount of time.
Ever since I got a DS4600 using standard RAID-5 I’ve been quite happy. Rebuild times on a 6TB volume are about 2.5 hours. Note: the volume is only about 1/3rd full, but it’s still way more data than what was on the Drobo in 2009.
Since that incident I strongly reconsider anything that implements something in a closed, proprietary fashion to replace a standard.
If you have one of the newer Drobo units and still have problems with the array rebuilding in an acceptable amount of time, let me know in the comments. I’d love to hear about it.