I'm relatively new to VMWare and have a question that relates to HA. I have HA installed and configured which has been tested and working properly this far. My environment is fairly straight forward with two hosts that share storage (VSphere 5). For sake of ease, let's say that I have 4 VM's working on each of my host machines. Each of these servers has 6 GB of RAM assigned to it so the actively used RAM is 24 GB. Each of the host machines has 48 GB of RAM so there is always 24 GB of free or available RAM if HA should need to use it. I need to add a 9th VM to the mix. So now one of my hosts (host A) has 30 GB of RAM assigned and 18 available. If either Host A or Host B were to go down, there now isn't sufficient RAM. So my question is, if there are 5 machines with 6 GB of RAM assigned each, does HA require the full 30 GB or does it take into consideration the amount of RAM the VM's are actively using. Say that each server was actively using no more than 4 GB of the allotted 6. Will HA then require only 20 GB or does it require the full 30 GB as assigned to the VM's?