BY BILL HENDERSON AND TRACY D. EDWARDS

IT organizations today face unprecedented requirements to keep pace with rapidly evolving business needs while maintaining continuous availability of mission-critical applications and keeping costs low. One consequence of the scramble to provide fast and flexible service is the tendency toward a sprawl of underutilized servers in the data center and an IT staff that is continually reacting to changing business conditions instead of proactively planning for growth. To rein in IT costs and keep enterprise applications running reliably without service interruptions, organizations are exploring ways to make their existing hardware resources do more.

Hardware virtualization offers the basis for a flexible, low-cost IT infrastructure that can provide the capability to respond immediately to changing business needs. By enabling a reduction in the total number of physical servers in the IT environment, a virtual computing infrastructure can help streamline systems management and reduce total cost ownership (TCO). At the same time, a virtual infrastructure can allow administrators to move application workloads easily from one physical server to another, facilitating seamless business continuity and disaster recovery.

Key to a virtual computing infrastructure is a software platform that provides a virtualization layer designed to decouple application workloads from the underlying hardware of the physical server. In this way, virtualization software can provide a set of virtual computing, memory, networking, and storage resources to each application. Virtualization software is designed to enable a single physical server to be divided into several independent virtual machines (VMs), each of which can host a separate “guest�? OS and associated applications in complete isolation from other VMs on the server (see Figure 1). The virtual infrastructure approach enables administrators to manage and optimize resources transparently across the data center.

The capability to run multiple VMs simultaneously on the same physical server enables enterprises to consolidate workloads from several separate physical servers onto one server, helping to reduce the number of physical servers required for a given workload. Unlike physical servers, VMs can be deployed in a matter of minutes and moved from one physical server to another without recon-figuring the OS, hardware, or applications. As a result, administrators can provision services quickly and allocate