Evaluation of disk-level workloads at different time-scales

In this paper, we characterize three different sets of disk-level traces collected from enterprise systems. The data sets differ in the granularity of the recorded information and are called accordingly the millisecond, the hour, and the lifetime traces. We analyze the disk-level utilization, the availability of idleness, the dynamics of the read and write traffic, over time and across an entire drive family. Our evaluation confirms that disk drives operate in moderate utilization and experience long stretches of idleness. The workload arriving at the disk is bursty across all time scales evaluated. Also, there is variability across drives of the same family, with a portion of them fully utilizing the available disk bandwidth for hours at a time.