The controller also might not take kindly to having a non-HP disk to deal with. If you got an HP SATA drive meant for that role, I'm sure it would work. I suppose you could try flashing a 2.5-in drive ...

I had the opportunity to experiment with a bunch of LSI1068E based SAS controllers. As everyone knows, a SAS controller is also fully capable of handling SATA disks. And you get a much better cable ...