Lots of info on some other sites.
I Have a 10 TB WD hard drive connected to an HS17 via a Thermaltake BlacX esata dock.
In past up to 2 TB on HR20's and 6TB (biggest available at the time) on HR54. All via Thermaltake esata docks.
The correct dock or esata enclosure is the important point. Some just don't work for unknown reasons. Others start up with no issues.