A friend of mine suggested this and I didn't like the idea of putting the OS on there especially that it is a virtual machine. There are a couple of things that made this setup nice though: PCIe bifurcation (4x4x4x4) lanes straight to the CPU and PCIe passthrough in ESXi. From what I read that ZFS needs direct access to the underlying hardware. So, I just treat the OS as totally disposable and not worth backing up. I can spin up a VM in less than 2 mins if something were to happen to it.