Virtualisation users must refocus on fragmentation issues

So goes the argument for virtualisation and hence also SANs and associated computing technology (storage are networks) upon which cloud-based solutions ultimately depend. But while these can greatly improve IT's ability to service a business, they come with age-old IT issues – solving some, but magnifying others, warns Diskeeper. "The concern of data security doesn't go away. In fact it can be argued the issue becomes even more important, largely due to the sharing of computing resources," explains Michael Materie, director of product technology at Diskeeper. He makes the obvious point that computing resources aren't infinite. IT managers challenged to build out and maintain computing infrastructures need to maximise use of the resources available, he says – and those are the same in the virtual world as they are in the physical – CPU, memory, network, and disk. Disk I/O performance has historically been the slowest of the primary components, and continues to be the weakest link, even with the advent of SANs, solid state drives and tiered storage systems. "Improving disk I/O performance typically provides the greatest increase in performance in modern virtualised infrastructures, just as it has in the past with physical servers and direct attached storage," asserts Materie. He points to data fragmentation, which occurs natively in all general purpose operating systems and causes more disk I/Os to be generated than necessary. "Due to sharing of resources in a virtual infrastructure, the issue becomes even more sifgnificant. The disk I/O traffic caused impacts not just on the culprit operating system, but all other operating systems that share that limited resource." Key to sorting this out is …… Because the SAN file system is managed at the hardware level by the SAN itself, and any client that attaches to it treats the SAN as local storage, the SAN manages its file system without regard for the way the server operating system writes data. So data needs to be written to the SAN in a way that minimises its fragmentation as it's written, allowing for fewer, but larger disk I/Os to be passed to the SAN. "Eliminating fragmentation reduces the number of disk I/Os required to accomplish business needs," states Materie. "If the same work can be done with less effort, that translates to lower costs and better performance." He suggests checking out Diskeeper's IntelliWrite, which, he claims, significantly reduces I/O bottlenecks by preventing fragmentation at source. "This technology … is essential for getting the full I/O performance from your computing systems," he says.