Summary: Purchased the 6TB model 9 months ago to use in a RAID 5 configuration for storage for our backup server. It was connected to a Mac via FireWire. Once it lost the FireWire connection causing the server to hang. Then one of the drives failed. They use Seagate 1.5TB drives. The lights on the back indicate what the 4big is doing. In this case it showed a rebuild in progress. Four days later, rebuild still in progress.