This guide is based on this blog post: http://blog.smartcore.net.au/blazingly-fast-afp-on-a-smartos-zone/.
Find the latest image, in this case 4166f6d6-ea5f-11e4-addd-8351b159d9b6 (15.1.0), or 24648664-e50c-11e4-be23-0349d0a5f3cf (14.4.1) if you need Long Term Support (LTS).
# imgadm avail | grep base-64