Virtual machine memory overview
When you create a new virtual machine, you set a fixed amount of memory using the creation wizard. According to what value you specify, XenServer will allocate this amount of memory to the guest.
Of course, you can change this value from the CPU and Memory section of the virtual machine properties.
Usually, you don't want to over-allocate memory to a virtual machine if it is not needed because this wastes physical memory. In the same way, you should prevent under-allocating memory because this creates poor performance. By default, when a Windows configuration achieves 75 percent of memory usage, it begins to access the page file and starts swapping.
The goal is to give the VMs the right amount of memory, monitoring the operating system performance and, especially when you have to deploy new applications on an existing or new virtual machine, checking all the applications' requirements in order to verify that a memory bottleneck will not occur on the guest virtual...
