Geoff,
Thanks, that does answer my question. Do you have a supported solution for my scenario? I'd like one RAID controller to be assigned to the ESXi host to contain a RAID-1 mirror of my VM datastore, and an entirely separate SATA controller (doesn't have to be RAID) to be passed through via VT-d to a virtual machine. That virtual machine will have direct control over that controller and will serve files using a ZFS mirror.
In terms of the backplane, it sounds like I can completely remove the backplane and simply have the drives expose their SATA connectors. I understand I lose quite a bit of flexibility (hot swap, etc...), but it also lets me have full control over which drives are connected to which controller. Is removing the backplane a supported configuration? I understand I would have to purchase cables that convert mini-SAS (on the PERC H310) to SATA.
Thanks!