We’re running a 2006 Xserve RAID at the university. Our old server was a 2006 Xserve with an Apple 2 Gbit Fibre Channel card. When we recently got a new Mac mini server to replace, we ordered an Atto Thunderlink FC 1082 to interface with the RAID. The Promise SANLink would have been a possible alternative, but the Thunderlink is capable of 8 Gbit/s, thus future-proofing our investment.
Unfortunately, when I hooked up the Thunderlink straight to the Xserve RAID using an Apple Fibre Channel Copper Cable, neither the Xserve RAID Admin utility nor the Mac mini showed a connection. After some googling around, it appears as if the Xserve RAID is not capable of negotiating links with HBAs that are capable of more than 2 Gbit/s. Turns out also says that you shouldn’t use their 4 Gbit card with the Xserve RAID: HT1769.
Since the RAID has been working fine for quite a while with two HP servers running VMWare ESXi with Qlogic QLE2460 controllers connected through a Qlogic SANbox 5200 2 Gbit FC switch, and I knew the Thunderlink worked with that switch, I simply used an FC Copper Cable between the Thunderlink and the switch and one between the switch and the RAID, configured the zoning, et voilà, the array mounted on the Mac mini.