Quote:RAID 6 addresses the lack of reliability of RAID 5 by allowing up to 2 HD failures out of 4 disks.
The problem with DROBO is that they use their own RAID-like format which is closed. Although it seems all nice and great from their website presentations, if the hardware fails and it's out of production or not repairable, then you might be out of luck: nothing will be able to read your data back since the format is unkown. This is not the case with traditional RAID solutions.
Traditional RAID solutions require identical disks (same manufacturer, same size) and that may also be challenging after 2 years ...