I been asked about how to size VMware vSAN solutions, both from Hardware Business Managers and Customers, this have been a manual calculation, with some help from different blogs.
Now VMware has released a online tool that you can help: https://vsansizer.vmware.com/
The result of the tool may be that you only need 3 hosts, which is the minimum, but you have to do some considerations, before deciding to only use 3 hosts.Duncan Epping has done a good blog article about why this may not be a good idea: http://www.yellow-bricks.com/2013/10/24/4-minimum-number-hosts-vsan-ask/
For choosing the hardware it’s can be done easier by looking at the VMware Virtual SAN Ready Node list: http://partnerweb.vmware.com/programs/vsan/Virtual%20SAN%20Ready%20Nodes.pdf
For complete list of supported hardware check the vSAN compability guide: http://www.vmware.com/resources/compatibility/search.php?deviceCategory=vsan