Virtual hardware and resource configuration
Appropriate virtual machine sizing as well as virtual hardware selection and configuration is an important part of the virtual machine design. Allocating too many resources can lead to waste and potentially even resource contention. Alternatively, if insufficient resources are provided to the virtual machines, it can cause resource issues as well as give users a poor impression of virtualization.
Generally speaking, it's easier to add more resources or virtual hardware to virtual machines than it is to take it away. Removing resources and virtual hardware can be difficult at times and almost always requires a reboot of the virtual machine. In some cases, a complete virtual machine rebuild is necessary. Often, resources or virtual hardware can be hot added to a virtual machine; the guest operating systems usually cope well with the addition too.
When sizing a virtual machine, begin with reasonable resource configurations. Benchmark the virtual machine...
