Are you using this in a G9 proliant with an HP or HP approved HBA (I guess not since you mention the M5210?) It is not guaranteed by HP to work if not, and I have seen problems with third party controllers. Are you using the cables that came with the controller or third party cables? There have been issues with cheaper third party cables and 12G SAS. The error you are getting is a Hardware Error sense code, that is the 0x04 in the sense code. It could be a hardware or a compatibility problem, unfortunately HP will not entertain the problem unless you are using it with a HP controller in an HP environment. 2.10 that you have installed is the latest firmware for that expander. I realize it isn't the answer you necessarily want, but HPE is very unfriendly to sompatibility with non-HPE hardware not on their HCL.