It is estimated that over 90% of all new information produced in the world is being stored on magnetic media, most of it on hard disk drives. Despite their importance, there is relatively little published work on the failure patterns of disk drives, and the key factors that affect their lifetime. Most available data are either based on extrapolation from accelerated aging experiments or from relatively modest sized field studies. Moreover, larger population studies rarely have the infrastructure in place to collect health signals from components in operation, which is critical information for detailed failure analysis.
We present data collected from detailed observations of a large disk drive population in a production Internet services deployment. The population observed is many times larger than that of previous studies. In addition to presenting failure statistics, we analyze the correlation between failures and several parameters generally believed to impact longevity.
Our analysis identifies several parameters from the drive’s self monitoring facility (SMART) that correlate highly with failures. Despite this high correlation, we conclude that models based on SMART parameters alone are unlikely to be useful for predicting individual drive failures. Surprisingly, we found that temperature and activity levels were much less correlated with drive failures than previously reported.
The full report (13 pages) is here in PDF format. It was written by Google Labs.
1 comment:
Based on what I've seen in large disk systems (nothing on the scale of Google, but systems with 100-200 HDDs in arrays), you can expect a failure rate close to 6-7% per year.
That's quite a substantial number, and this is the reason that you should never trust important information to a single disk drive. Have redundancy for disk failures via RAID 1 or 5, or another RAID level that provides for disk failures. And backup everything you really need to keep to tape.
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