MTBF

Abbreviation for Mean Time Between Failure. MTBF Is a statistical term relating to reliability as expressed in power on hours (p.o.h.) and is often a specification associated with hard drive mechanisms. It was originally developed for the military and can be calculated several different ways, yielding substantially different results. It is common to see MTBF ratings between 300,000 and 1,000,000 hours for hard disk drive mechanisms, which might lead you to conclude that the specification promises between 30 and 100 years of continuous operation. This is not the case! The specification is based on a large (statistically significant) number of drives running continuously at a test site with data extrapolated according to various known statistical models to yield the results. Based on the observed error rate over a few weeks or months, the MTBF is estimated and not representative of how long your drive, or any individual product, is likely to last, nor is it a warranty. It is representative of the relative reliability of a family of products. A higher MTBF merely suggests a more reliable and robust family of mechanisms (depending upon the consistency of the statistical models used).