I came across a reference to the paper "Availability in Globally Distributed Storage Systems" where the authors state the following in a table (check Table 2)
Now reading this, it looks like the mean value for a disk failure ranges between 10-50 years!
If I remember correctly, the mean or average is a single value and not a range?
How should I interpret this?
Does it mean that the statistical data available isn't reliable or there is a big difference between different samples or reports?
I would guess that they were working from data that had hard drives categorized by brand, size, technology, or something similar. Rather that take the overall mean, which might require finding out how many of each kind there are, they just report the range of means. In the text they point out that the drive failures do not contribute much to unavailability, so the MTTF of drives is not important as long as it is at least 10 years.