I. Executive Summary
Computer virtualization software is a new innovative technology that allows a single desktop computer to run several different operating systems at one time. The single desktop is known as the physical server or host and the other operating systems are known as virtual servers or guests. Computer virtualization was developed because of one simple idea: utilizing hardware. In the 1960s it was first developed in order to partition large, mainframe hardware for better hardware utilization. IBM first implemented it more than thirty years ago as a way to logically partition mainframe computers into separate virtual machines. This partitioning that IBM instated allowed mainframes to multi-task meaning they could run several applications and processes at the same time. Some users who have attested to the greatness of computer virtualization are the U.S. Census Bureau, Mechanics Bank, and Illinois’s Kane County Government.
II. Technology Description
There are three different types of computer virtualization: full virtualization, para-virtualization, and OS-level virtualization. Full virtualization uses a special type of software called a hypervisor. The hypervisor interacts directly with the physical server’s CPU and disk space. It serves as a platform for the virtual server’s operating systems by keeping each virtual sever completely unaware and independent of the other virtual servers that are running on the host. If a business or other customer uses full virtualization they are able to run several different operating systems on the host. For example, the host computer could be running on a Mac but the virtual server could be running as Windows. Para-virtualization is almost exactly the same as full-virtualization; however, there is one distinct difference between the two types. Full-virtualization’s virtual servers are completely unaware of each other but para-virtualization’s virtual servers are completely aware of one another. This awareness in para-virtualization allows the hypervisor to use as much processing power since the virtual servers already are aware of the demands that each virtual server is making of the physical server. OS-level virtualization is completely different compared to the other two types of virtualization. OS-level virtualization does not use a hypervisor at all; all the virtualization capability in this particular software rests solely on its host operating system. Since the virtualization capability is embedded in the host operating system, all of its virtual servers must run on the same operating system as its host; which is also known as a homogeneous environment.
Choosing between these three different types can be challenging but once the administrator understands their own needs, picking the type becomes much easier. One would choose an OS-level virtualization if they do not need different operating systems on the host. One would choose para-virtualization if they wanted to be able to run different operating systems on their physical server and if they were comfortable with using a relatively new technology. It is the newest type of virtualization and thus lacks the technical support that the other types have since it has not been around for very long. Therefore, if someone wanted a virtualization software that could run different operating systems on the physical server but wanted sufficient technical support then they should choose full-virtualization.
III. Business Impact
The benefits of computer virtualization are many but the main reasons to use computer virtualization are consolidation, saving time, money, and space, utilization of hardware, and redundancy as a safety measure. Overall, virtualization allows the customer to save time, space, and money while increasing the amount that one physical server can do. It also allows companies to use redundancy as a safety measure by allowing many physical servers to run the same virtual servers and applications just in case one of the systems breaks down; it also eliminates the problem of interruption time.
Another benefit of server virtualization is that eventually, like with most technology, the company’s hardware is going to become outdated and useless. The time, money, and effort that must be invested in going from one server to another is a lot and can be avoided with something called a legacy system. The company’s IT department can create a virtual version of the hardware on their current systems. It will have no impact on the company’s day to day work. The benefit of this process is that it gives the company time to get ready to transition to the new system without having to worry about any hardware failures. Companies also have the luxury of being able to control who gets to use which virtual server, thus creating an extra security measure in order to make sure those who aren't suppose to see certain information do not.
IV. Limitations
Like with anything else in life, there are also some limitations that come with using server virtualization. For servers that use a lot of processing power due to the applications and other programs on it, server virtualization is not recommended. Server virtualization basically divides the processing power among the number of servers present. When the processing power can not meet the demands, everything gets slowed down. Tasks that might not otherwise take that much time, could possibly take hours and there is a high chance that a server might crash.
Another limitation of using server virtualization is using too many virtual servers on one physical server. The reason being is that if the number of virtual machines that a physical server must support increases, the processing power that the server receives decreases. Also, there is a limited amount of hard drive space on physical servers so the amount of virtual servers can impact its ability to store and retain data. Migration can also be an issue because it is only possible to migrate a virtual server from one physical server to another only if both of the physical servers are using processors from the same manufacturer.
With these limitations, it is important to remember that the good it can do for a company can be great, only if it is used under the correct circumstances. So if a company that might not need it, invests in its technology, it could be a bad decision on their part. The full potential of these servers and the technology that comes with it has not been fully achieved, and with time the possibilities that it has in the IT world as well in our day to day lives can be numerous.
http://show.zoho.com/public/misdomgeorge/Computer%20Virtualization
Bibliography
http://communication.howstuffworks.com/server-virtualization.htm
http://www.vmware.com
http://www.techsoup.org/learningcenter/software/page4826.cfm
http://business-software.suite101.com/article.cfm/computer_virtualization_advantages
http://www.vmware.com/files/pdf/customers/05Q1_cs_vmw_Mechanics_Banks_english.pdf
