With vSphere 5.5 about to go GA, something that people may not know is that there’s an uplift in the host minimum memory requirement. I noticed early in the beta process that if I configured a host with only 2GB of RAM (the previous maximum) while it would install and run fine, as soon as I joined it to a cluster the host would PSOD. I soon learned that the memory footprint of ESXi has increased by a little bit, as soon as the FDM service was started, it would tip over the edge.
So, with that in mind I had to increase my nested hosts to 3GB to get them to run properly… when you add in VSAN and any other services needed, you may find that even that is not enough. ESXi 5.5 “officially” requires a minimum of 4GB of RAM.
Time to upgrade those lab hosts!