Disk Infant Mortality in Large Storage Systems

Appeared in Proceedings of the 13th International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunication Systems (MASCOTS '05).

Abstract

As disk drives have dropped in price relative to tape, the desire for the convenience and speed of online access to large data repositories has led to the deployment of petabyte-scale disk farms with thousands of disks. Unfortunately, the very large size of these repositories renders them vulnerable to previously rare failure modes such as multiple, unrelated disk failures leading to data loss. While some business models, such as free email servers, may be able to tolerate some occurrence of data loss, others, including premium online services and storage of simulation results at a national laboratory, cannot.

This paper describes the effect of infant mortality on long-term failure rates of systems that must preserve their data for decades. Our failure models incorporate the well-known “bathtub curve,” which reflects the higher failure rates of new disk drives, a lower, constant failure rate during the remainder of the design life span, and increased failure rates as components wear out. Large systems are vulnerable to the “cohort effect” that occurs when many disks are simultaneously replaced by new disks. Our more accurate disk models and simulations have yielded predictions of system lifetimes that are more pessimistic than existing models that assume a constant disk failure rate. Thus, larger system scale requires designers to take disk infant mortality into account.

Publication date:
September 2005

Authors:
Qin Xin
Thomas Schwarz
Ethan L. Miller

Projects:
Ultra-Large Scale Storage

Available media

Full paper text: PDF

Bibtex entry

@inproceedings{xin-mascots05,
  author       = {Qin Xin and Thomas Schwarz and Ethan L. Miller},
  title        = {Disk Infant Mortality in Large Storage Systems},
  booktitle    = {Proceedings of the 13th International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunication Systems (MASCOTS '05)},
  month        = sep,
  year         = {2005},
}