Virtualization Workstations
Hardware virtualization has taken the industry by storm and has given rise to entire companies and large business units in existing companies that provide software and algorithms of varying effectiveness for the purpose of minimizing the hardware footprint required to implement multiple servers and workstations. Although virtualization as a technology subculture is discussed in greater detail later in this book, you are ready to investigate the unique requirements for the workstation that will host the guest operating systems and their applications.
Virtualization workstations must exceed the specifications of standard servers and workstations in two primary areas:
- CPU enhancements
- Maximized RAM
Depending on the specific guest systems and processes that the workstation will host, it may be necessary to increase the hard drive capacity of the workstation as well. Because this is only a possibility, increased drive capacity is not considered a primary enhancement for virtualization workstations.
Virtual machines (VMs) running on a host system appear to come along with their own resources. A quick look in the Device Manager utility of a guest operating system leads you to believe it has its own components and does not require nor interfere with any resources on the host. This is not true, however. The following list includes some of the more important components that are shared by the host and all guest operating systems:
- CPU cycles
- System memory
- Drive storage space
- Systemwide network bandwidth
CPU Enhancements
Because the physical host’s processor is shared by all operating systems running, virtual or not, it behooves you to implement virtual machines on a host with as many CPUs as possible. The operating system is capable of treating each core in a multicore processor separately and creating virtual CPUs for the VMs from them. Therefore, the more CPUs you can install in a workstation, each with as many cores as possible, the more dedicated CPU cycles that can be assigned to each virtual machine.
Maximized RAM
As you create a virtual machine, even before a guest operating system is installed in the VM, you must decide how much RAM the guest system will require. The same minimum requirements for installing an operating system on a conventional machine apply to the installation of that operating system on a virtual machine.
The RAM you dedicate to that VM is not used until the VM is booted. Once it is booted, though, that RAM is as good as unavailable to the host operating system. As a result, you must ensure that the virtualization workstation is equipped with enough RAM to handle its own needs as well as those of all guests that could run simultaneously. As with a conventional system running a single operating system at a time, you generally want to supply each VM with additional RAM to keep it humming along nicely.
This cumulative RAM must be accounted for in the physical configuration of the virtualization workstation. In most cases, this will result in maximizing the amount of RAM installed in the computer. The maximum installed RAM hinges on three primary constraints:
- The CPU’s address-bus width
- The operating system’s maximum supported RAM
- The motherboard’s maximum supported RAM
The smallest of these constraints dictates the maximum RAM you will be able to use in the workstation. Attention to each of these limitations should be exercised in the selection of the workstation to be used to host guest operating systems and their applications. Considering the limitations of operating systems leads to preferring the use of server versions over client versions and the use of x64 versions over x86 versions.
