erver remotely for computing related to their research. Markley supplies the physical security, security from hackers, cooling, and "hardened" building construction to protect their facility from natural disasters such as hurricanes and earthquakes. www.TechnicalPDF.com Cloud companies sell multi-tenant platforms (servers) where customers can spin applications up to or down from the cloud. Providers offer more granular, finer tuned services. For example, customers can control the days and hours their applications are available, the amount of cloud security they require, and whether to pay extra for their own, private server. They have the ability to more granularly measure and control computing power and usage on their applications. Cloud providers also offer Service Level Agreements (SLAs) that spell out guarantees of up-time and other performance criteria. Typically, hosting companies charge flat monthly fees and cloud providers' charges are metered, based on monthly computer usage. Often an organization will consolidate applications that are not in the cloud into central data centers that were previously located in numerous remote offices and department. Centralization and streamlined data center operations are enabled in large part by storage, server, and switch virtualization. Increased broadband network capacity is another key enabler of centralized data centers. Environmental Controls in Data Centers Virtualization and cloud computing have decreased the number of physical servers needed in data centers. However, each physical server requires more cooling due to more powerful, octal processors that generate more heat than dual or single processors. This increases electricity costs needed for cooling these powerful servers. Designing cooling, power, and Uninterrupted Power Supply (UPS) systems that distribute power are SO complex that organizations often hire consultants to www.TechnicalPDF.com design cost-effective environmental controls. An uninterrupted power supply provides power for the short time befor