Benefits of Virtualization

It should be apparent from the previous few pages that virtualization offers companies a new level of flexibility in server deployment and management not possible using only physical hardware. This section summaries some of the benefits that organizations can realize from hardware virtualization:

• Fewer Physical Servers—By virtualizing servers, an organization requires fewer physical servers. Because modern physical servers support multiple physical processors (with, in some cases, up to 12 cores or more per processor), and up to 384GB or more of RAM, companies can increase their consolidation ratios (ratio of virtual servers to physical servers) by placing more and more virtual machines on the same physical hardware.

• Infrastructure Flexibility—As physical servers begin to demand hardware upgrades, the traditional model required organizations to purchase new servers, or more memory or processing power. In a virtual environment, administrators can easily shut down a virtual machine and add more virtual memory or processors or even move the virtual machine to a new host with more hardware resources. Some hypervisors and operating systems even allow these configuration changes to happen without shutting down the virtual machine. Additionally, expanding the infrastructure to accommodate new virtual machines can become a simple matter of adding a new physical host to the cluster. This adds an entirely new level of flexibility to managing server resources.

• Increased Availability—In physical environments, servers were often built to be as redundant as possible with multiple hard drives and power supplies. These additional expenses are still useful for a host server but do not apply to virtual machines. As long as a virtual machine image is made highly available, it can be easily restarted on a different host if a physical host fails. It is still best practice to design the hosts to be fault tolerant, but the additional expense of designing every single server for hardware redundancy becomes unnecessary. Organizations can achieve a higher level of service and availability for servers by abstracting the hardware layer through virtualization.

• Reduced Operating Expenses—By reducing the number of physical servers in the environment, organizations can also realize decreased operating expenses associated with physical servers, such as rack space, cooling, and power.

• Application Isolation—A significant challenge in the days of using only physical servers was that each new server required its own physical hardware. Best practice is to isolate each application to a specific server. Typically, this was difficult because of the additional expense involved in purchasing and installing a new dedicated server for each application. To work around budget issues, administrators began to collocate different applications on the same physical server, but because application vendors usually only test and expect their application to have its own dedicated environment, this could cause performance or configuration issues that were difficult to troubleshoot. With virtualization, each application can have its own dedicated server virtual machine.

• Legacy Application Support—An unfortunate reality for many organizations is a need to support legacy applications that run on only legacy operating systems. As the hardware these systems run on begins to fail or needs replacement, without virtualization, organizations must redeploy these applications on new hardware or operating systems not certified for the product and incur the expense and complexity of redeploying the legacy application. Using virtualization, however, companies can create a new virtual machine running a legacy operating system very easily. They can also perform a physical-to-virtual (P2V) migration of the existing physical server to copy it as-is from a physical to a virtual machine.