The central idea behind virtualization is to make it seem that computer hardware has greater capacities than it actually does. There are many ways to accomplish this, so you must keep certain things in mind as you decide the best virtualization strategy for your needs. To choose the best strategy, consider whether your computer network has experienced a sudden increase in the number of servers used, how much money is available to spend on virtualization and how much control you need over resources.
Virtualization in the field of computers has been around for a very long time. The early mainframes used paging techniques for virtualization of storage, meaning main memory. Auxiliary or disk storage was virtualized through the use of storage area networks (SANs) and networked attached storage (NAS). Virtualization has been extended to include computer and network resources. From one large virtualization server, many other servers running different operating systems can be carved. A portion of available network can be assigned, and all of this is done through virtualization software.
A virtualization strategy may be to replace many discrete servers, each running an operating system and one or a few applications, with a few large virtualization servers. The beauty of this virtualization strategy involves saving data center space and other resource overheads such as power, network drops and air conditioning. This virtualization strategy is best for organizations that have experienced server sprawl during growth spurts and from the acquistion of other companies.
Another virtualization strategy involves the use of cloud computing. Cloud computing is when a large data center, such as an online company, offers virtualization servers on a rental basis. For a monthly fee, the customer can carve out multiple servers with different capacities, storage to support databases and other applications and a portion of network bandwidth.
The upside of this virtualization strategy is the low cost, because only those resources that are needed to support the applications are billed. The downside is that your organization will not have full control of the resources. This virtualization strategy means trusting another company or organization to keep the virtual machines running all the time. As a result of this, the trend has developed to keep mission-critical applications in-house and back-office applications in the cloud. Notable exceptions to this virtualization strategy are web applications that do not require rock-solid availability.
As time goes on, it is feasible cloud computing could become solid enough to support mission-critical applications. An old saying in the computer field, however, is that what can go wrong will go wrong — and at the most inopportune times. The best virtualization strategy will keep these timeless principles in mind.