> For a MTBF of 2 million hours, that means that on average, if you have one thousand drives, then you should expect one drive failure every 2000 hours That as

> For a MTBF of 2 million hours, that means that on average, if you have one thousand drives, then you should expect one drive failure every 2000 hours That assumes your drives fail with a constant independent probability, like nuclear decay events (Poisson distribution). The reality is more like https://en.wikipedia.org/wiki/Bathtub_curve https://en.wikipedia.org/wiki/Bathtub_curve . MTBF is not a good metric for complex systems used under wildly-varying load conditions, but ... it's a metric.