I dont think the Microserver supports VT-d so I wouldnt plan on using passthrough, although you may be able to use it as a RAID card in ESXi if you have the BBWU/cache.
Just a thought, are you using 1vCPU per VM? If you are you probably shouldnt be. Whats your CPU usage during a write action? I have tried Freenas but quickly abandoned it so Im no expert, perhaps the Freenas forums could be of more help?
Ofcourse using 1vCPU per VM, it's my day to day job running vSphere farms so luckily I knew that one
CPU Usage was quite ok even memory, but the disk latencies skyrocketed like I have never seen on another system.
Just as a test I moved ESXi and the Freenas VM + disks to my desktop system (quad-core amd) and performance more than doubled especially writes.
Also disk latencies were around 20-30 milliseconds, so much better than on the N40L.
I know it doesn't support VT-d, a colleague of mine owns it now, for him it's good enough
I've bought the Gigabyte B75M-D3H and an i5-3550. Going to try some underclocking/volting and hope too bring it down enough to have a low power consumption and be stable.
Don't know the difference in power usage on motherboards from Gigabyte and MSI.
Finally a decent ESXi Box so I can reinstall my home labo.
What type of memory do you have installed and what voltages are you running at? Just to give me an indication of what I can aim for.