Virtualization Essentials

Tuning Practices for VM Memory

Context is important when you’re working with memory in a virtual environment. So far we have looked at memory only from the standpoint of the virtual machine looking outward. The amount of memory that has been allocated to the virtual machine is what it can use. The physical host it resides on may have hundreds of gigabytes available but each individual virtual machine is unaware of the greater resources. Figure 8.4 shows a simple illustration of this model. The two virtual machines have been allocated 4 GB and 2 GB of memory, respectively, and that is all the memory that the guest operating systems in those virtual machines are aware of. The physical host actually has 16 GB of physical memory. With 6 GB of memory ...