Improving disk performance via latency reduction

It is shown that in many environments the rotational latency and the rotational position sensing (RPS) miss delay are the major contributors to a disk's basic service time. A sensitivity study using a simple analytical queueing model shows that a reduction in these two components (both of which are related to the rotation of disk drives) has the greatest impact in reducing the disk's basic service time and in turn produces the greatest improvement in overall subsystem performance. While the most straightforward way to reduce latency and RPS miss penalty would be to increase the disk's rotation speed, there are some limitations to such an approach. Several alternatives to reducing latency and RPS miss penalty are proposed and explored, and their performance is analyzed using analytical queuing models.<>