Where virtualization got its start Toward the fully virtualized data center The drivers A missing piece An IT checklist Virtualization milestones The utility data center

For years, server and storage management have been on parallel, but separate, technology development tracks. IT executives, confronted with quickly multiplying numbers of servers and storage arrays, put them there. They've needed to treat these platforms as distinct entities that require different networks, management strategies and even staffs to maintain efficiencies within the data center.

But as companies roll out data center architectures, these two islands need to blend. Convergence, required to further simplify and improve data center efficiencies, will be quite possible with the array of new and emerging technologies. These include data center service management and automation tools, blade servers, utility and grid computing, storage-area networks (SAN), grid storage, information life-cycle management (ILM), policy-based management tools and the all-important virtualization.

Virtualization is not a new concept in the server or storage markets. Companies already are benefiting from the ability to create distinct server and storage resource pools, masking the physical components from users and applications. But integrated server and storage virtualization holds the key to true management convergence.

Where virtualization got its start

In the server market, virtualization surfaced initially for use with mainframes. In this environment, virtualization tools assisted in workload management and improved utilization.

In the late 1990s, virtualization tools emerged for Unix and Windows servers. These let multiple virtual operating systems run on one physical machine but be logically independent with consistent hardware profiles. Sometimes referred to as server resource management, these tools include partition managers, virtual machines, virtual partitions and logical partitions. Such tools have grown in importance as a means to improve server utilization rates, as well as to better align and manage application performance on different server platforms, ranging from blade servers to large symmetrical multiprocessing systems.

In storage, the earliest use of virtualization emerged in the early 1990s with the first RAID subsystems, which essentially combined that technology with aggregation. By the late '90s, in came storage virtualization appliances aimed at improving management and utilization. Since then, storage virtualization has evolved from a stand-alone technology to a feature of storage infrastructure management tools. This means it resides on host servers, on storage arrays or, increasingly, on intelligent switches in the storage network.