In ESX cluster with 3 host I have some WIndows 2003 Server Standard x64 machines with 16GB RAM.
In VM Settings "Windows 2003 Server x64 Standard" is selected. The recommended max RAM size by VMware is 4GB according to the menu when creating the machine. I assigned 16GB to my machines, because the OS I installed supports up to 32GB. Now the VM are performing very slow, time to boot ist up to 10 minutes. The VMs are creating heavy CPU Load on the Host when booting.
I changed the OS selection to "Windows 2003 Server x64 Enterprise". Now everything is fine.
What causes this behavior? Can it possibly be that ESX is only assigning the recommended RAM as physical RAM to the VM and the rest is swapped to the disk?