How do physical disks passed through ESXi perform vs. passing through HBAs?

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http://serverfault.com – Context: I have a SAN operating system (Nexenta) that runs on ESXi. It has a couple of HBAs passed through to it already, via VT-d. All of the HBAs for the SAN OS are full (no free connectors). I recently purchased some SATA SSDs for Nexenta and attached them directly to the motherboard's on-board SATA controller. I can add those new SSDs to the Nexenta VM by adding "physical disks" to the VM profile in vSphere. Alternatively, I could connect then to one of the HBAs, but I'd have to disconnect/move existing disks, which entails considerable hassle. Question: My question is: assuming that (HowTos)