I have a EMC DAE (KTN-STL4) drive cage directly connecconnected to a HP Proliant server using a QLogic QLE2560 HBA. I'm using copper cable between the HBA card and the DAE. On the controller card in the DAE there is a label that states "4Gb". I'm guessing that this means 4Gbit/s. But if I set the HBA card to "Auto speed" it negotiate 2Gbit/s, and if I hard set it to 4Gbit/s I end up with no link.

Why is this? Isn't the DAE controller card capebel of link speed higher then 2Gbit/s or is it the copper cable that limits the speed, or is it the interface used between the DAE and Qlogic HBA that is the problem? I have been browsing for HSSDC-FC converters and they always seems to på rated at ~2Gbit/s. If this is the limit, why does it say 4Gb on the controller cards in the DAE?