Currently I have 3 VMware hosts (2 Mac Minis and a Dell Server) with a pair of Synology NAS units running in high availability mode. As I found out the hard way - it turns out a backup is still required as my datastore got corrected and I narrowly escaped some serious dataloss. Perhaps not using the high availability mode is best and breaking them up into two separate NAS units with a primary and backup. I'm not sure how backing up virtual machines works so please run me through my options for software and all. This is a home office setup (I go all out with my stuff) so there is something to be said for being budget conscious.