Disks Are Like Snowflakes: No Two Are Alike
Gone are the days of homogeneous sets of disks. Even disks of a given batch, of the same make and model, will have significantly different bandwidths. This paper describes the disk technology trends responsible for the now-inherent heterogeneity of multi-disk systems and disk-based clusters, provides measurements quantifying it, and discusses its implications for system designers. Many multi-component systems are designed and built assuming uniformity of performance. People buy identical hardware, use the same configuration, and expect to achieve similar performance.