To my surprise, I have been seeing storage performance results reported using server benchmarks and their associated server metrics. Server benchmarks are specifically designed to measure the maximum performance of the server — NOT the storage.
Even if external storage is used in the benchmarked system, server benchmarks entail maximizing the performance limits of the server’s processing power. Often times, in cases where storage performance is measured by a server benchmark, the server and OS are not even tuned or optimized, and the storage is not offered the full load it can handle. This means that storage performance is ‘left on the table,’ and the primary metrics reported are skewed. These skewed metrics do not reflect the true performance of the external storage array.
For example, VMmark benchmark was specifically designed to measure how many virtual machines under active business application load a server can handle. If the I/O activity is measured during this benchmark, it will show that the I/O load is light-to-medium on the average external storage array. That means even though the server running the benchmark may reach its maximum performance, the storage could handle more I/O activity.