eventually, hopefully freenas will iron out the bugs with esxi and hyper-v
There are no "bugs" with ESXi. It works swimmingly well. The problem is that most new users have absolutely no idea how to do it correctly, and if you do it incorrectly, then you are at significant risk of catastrophic data loss.
1) You can use known-good server-grade hardware with VT-d and the magic formula
I've previously provided. This is closest to what users seem to hope for, but it's going to be all tears when you need to reinstall ESXi and it helpfully formats all your disks as datastores.
2) You can provide properly redundant datastores (not RAID0!) to reduce the chances of hypervisor I/O hangs and then build normal virtual disks on top. Note that you have to ALSO provide redundancy at the FreeNAS level for ZFS to be able to correct bitrot issues, otherwise more sadness. Almost no one in these forums is interested in this, because it uses up LOTS of disk space, but it DOES work.
3) You can do pretty much any other dumbshit thing you'd like to and it will work right up to the point where something you failed to anticipate happens and (in the worst case) eats your data. That includes the obvious variation on #1) that involves substituting RDM for VT-d, or the obvious variation on #2) that involves using nonredundant ESXi datastores.
The bug isn't in FreeNAS or in ESXi. It is in the user's head,
because at the end of the day the users always want cheaper, faster, and bigger, and will cut corners to get there. Virtualization allows this but when your system commits seppuku on you with your poorly thought out virtualization strategy, the complexity of recovery is going to be beyond what you'll get helpwise in the forum, if recovery is even possible.
So I am now officially tired of explaining this and people are warned against begging for virtualization help in this thread
You can run Virtualbox VMs in a jail on bare metal FreeNAS and use spare resources that way. It comes with essentially none of the drawbacks of virtualizing FreeNAS itself.
This, however, is the single most helpful response in recent days. I heartily endorse this as a third relatively safe solution for resource sharing. I am also hoping that we see bhyve support in FreeNAS 10. ;-)