I am really confused about what I was just told by support on the phone. Maybe it was some of the language barrier between myself and tech support, so I'm posting on here for some follow up. Just for info sake, I have 2 ESXi hosts. Each has 96GB of memory. Today I added the 2nd host to my environment and the 2nd host was pre-installed with 5.1, so I upgraded my original host form 5.0 to 5.1. The upgrade process went fine, no problems/errors. I went to power back on the VM's on my original host, and I was getting the error: "A general system error occurred: The virtual machine could not start". I phone into tech support and 45 minutes later of him troubleshooting he tells me that I was trying to use too much memory on my VM's. On my host I had 3 VM's. 1 set to use 4GB, 1 to use 4GB, and another to use 48GB. He told me I needed to reduce the amount of memory used in the 48GB host to 30GB and that would fix the problem. I didn't believe him, but we reduced the memory and sure enough everything worked again. I asked why we had to reduce the memory and he said you can only use 1/2 of the memory in your server. That made absolutely no sense to me, why can you only use 1/2 of the memory? Furthermore, before the upgrade I was using almost 85GB of my 96GB of memory on that host. I have sense moved over some of my VM's onto my new host.
Can someone please clarify why I am only able to use 1/2 of the memory available on my ESXi servers, and why I was able to use 95% of it in ESXi 5.0 but not 5.1 ?
