Server virtualization rollouts often get stuck after the first wave. That first wave is where you have virtualized most of your easy stuff. Then as the virtual machines begin to proliferate, it occurs to you that you have lost control. One of the key disconnects is from server to storage.Back in the old days of direct attached storage (DAS), you knew exactly where your application was getting its data and where to identify bottlenecks. That said, DAS certainly had its limitations. Those limitations were in large part resolved by storage area networks (SAN) and despite the complexity they brought to the data center, SANs were deemed "worth it." There was a layer of abstraction that caused some confusion with a SAN. The storage is separated from the server, but at least you still had one application to one server.

Server virtualization adds another layer of abstraction to the equation -- now multiple virtual servers from the same physical host are attached to your SAN. Additionally, those virtual servers begin to move from physical host to physical host. Storage management in a virtualized server environment becomes very challenging.

The process bogs down when you try to virtualize more of your existing servers or someone presents you a request for a new virtual server. Typically, one of your first steps will be to determine which physical host has the most available compute, memory, network, and storage resources available to it. The problem is getting a view that lets you "see" from the virtual cluster all the way through to storage. For example, tools like Tek-Tools Software's Profiler for VMware, Akorri's BalancePoint, and others provide capabilities that allow you to see how storage, virtual machines, and their physical hosts interact.

In a world where you have to do more with less, these solutions increase your efficiency by allowing you to better plan and optimize your virtual moves. For example, if you have a physical server that you are planning to virtualize, you can use these tools to see where your available capacity is by physical host or by the entire virtual cluster. You can then place your new virtual machine on the server with the most available storage capacity both from a space standpoint as well as I/O availability. Tek-Tools extends this a step further if you are using its other modules and will rank the hosts in your environment as to their favorability to be virtualized.

Using tools like this will increase ROI on your virtualization project by allowing you safe but maximum utilization out of your physical infrastructure while at the same time increasing your flexibility to respond to changing business requirements.

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George Crump is founder of Storage Switzerland, an analyst firm focused on the virtualization and storage marketplaces. It provides strategic consulting and analysis to storage users, suppliers, and integrators. An industry veteran of more than 25 years, Crump has held engineering and sales positions at various IT industry manufacturers and integrators. Prior to Storage Switzerland, he was CTO at one of the nation's largest integrators.