Howard Marks writing for Network Computing comments:

The folks at Backblaze, the online backup service that’s probably as well known for its  ultra-low cost storage pods  as it is for its core business, recently released some data based on its experience with more than 25,000 disk drives. As anyone who read the  Google  and  Carnegie Mellonstudies a few years ago would expect, disk drives in the real world fail at a much higher rate than the under 1% per year vendors tout on their spec sheets.

Drives die. It’s a certainty. They won’t keep spinning forever. But do you know what really causes failure? Or how often?

Read more at: Disk Drive Failure: An Unavoidable Reality