I don't use FreeNAS anymore. I've switched to an Ubuntu storage-focused VM with ZFS on Linux (ZoL) and Docker. This is because Docker is a Linux technology and FreeNAS is FreeBSD-based. If I was to run ZFS, I'd need to run Docker in a separate VM. Having Docker and my storage together means I can map my storage directories straight into my Docker instances, without needing an underlying network file system. This theoretically should give better performance.