There are four major steps on the road to a flexible data center: consolidation, standardization, virtualization and utility (see "Four steps to utility," . A company may choose one area, say storage, to start on the utility roadmap. Some companies may attempt to push all aspects of the data center towards utility. While the effort is not without challenges, it can bring benefits, especially in the form of reduced operational costs and greater agility. In this article, we will examine the challenges and implications of embarking on the third step: virtualization.

* Storage virtualization

Storage virtualization has been a hot topic for at least the last two years. It occurs at two levels: block storage and file storage. Storage teams can implement virtualization of storage-area network storage to present several different physical storage racks as a single virtual storage pool.

Using virtual SANs you can further virtualize storage by offering multiple separate and isolated virtual SANs from the same pool. In file-based storage, companies can virtualize the network-attached storage, creating virtual file systems from a pool of several NAS devices. Additionally, file storage can be delivered virtually from underlying SAN block storage, where a NAS gateway presents a virtual file system that is stored on blocks of a virtual SAN (see "Storage leads the way to next-gen data center,".

* Computing

Computing virtualization is also growing very fast. Some of the leading companies in the space have developed cross-platform server virtualization software that allows data center managers to cluster and partition servers. With these tools, a single physical server can either offer multiple virtual servers, or be consolidated into a cluster that acts as a single server (see "Virtualization and clustering: combining two winning strategies,".

* Networking

Networking virtualization can occur at the LAN or the WAN. On the LAN, virtual LAN technology allows network managers to create isolation and segmentation into virtual LANs running on a single physical LAN. On the WAN side, the same effect can be achieved with MPLS, a technology that offers partitioning of WANs into multiple isolated virtual WANs running on a single physical infrastructure. Virtualization can bring higher utilization, better security and easier management.