Both server virtualization and desktop virtualization use a software core called a hypervisor to run multiple operating systems on the same physical server hardware. Each OS is kept separate, with resources dedicated as needed.
Since you can buy modern servers with multiple CPUs, large amount of memory, lots of storage, and high-bandwidth network connections, each OS can have as much computing power at need as an individual server might provide. The operating systems and applications seldom use all available resources, especially at the same times--so more operating systems and applications can coexist on a single piece of hardware, resulting in better utilization of hardware.
If you're not using virtualization now, you should be thinking about it. Here's why.
1. It enables you to get the most out of your server hardware.
Many servers typically run for most of the day at very low levels of utilization. Adding multiple OSs and applications helps you get the most out of those expensive server resources. Since many virtual machines can run on one server, you substantially reduce the total expenditure for hardware.
2. It will allow you to set up redundant servers for better fault tolerance.
Hypervisors allow OSs and their applications to be migrated from one system to another. If one hardware server or the operating systems and applications running on it fail, those OSs and applications can be moved to another hypervisor running on a different physical server. Big servers are typically set up for better fault tolerance than small servers. Two big servers, for instance, can allow for migration of applications and provide better fault tolerance than a dozen small servers, while using less energy and being easier to manage.
3. Management is simplified.
Since all the operating systems on a hypervisor can be administered through a single interface, and systems can be given more computing resources as needed, it can be much easier to manage a dozen virtual servers than a dozen separate physical systems. Each operating system must still be managed separately, but add-on tools are available to simplify that process as well.
4. You can partition applications on separate OSs for greater reliability.
Normally, a physical server will run one operating system, and that OS will have multiple server applications installed on it--a Web server, email server, database server, and so forth. However, running multiple server applications on a single OS increases the possibility that one application may interfere with another, causing bottlenecks or even crashes. By partitioning applications in different virtual machines, each application has its own OS and resources, and is less likely to interfere with other applications.
5. Provisioning new servers for prototyping, testing and migration is simplified.
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