This piece covers a finding by Google engineers that in some ways contradicts commonly heald beliefs that high temperatures and/or high utilization will cause a hard disk to fail sooner.

Basically, they found that there is a weak coorelation between temp and failure rates. It also found that drives up to 3 years old that are used infrequently are more likely to fail than those that have a high utilization.

They also found that a drive with any scan errors (surface errors) is 39 times more likely to fail than a drive with none.

What I took away was this:
- Expect to replace drives after 3 years
- If a drive is showing scan errors, replace it.
- Don’t worry so much about temp & ‘thrashing’.

BBC NEWS | Technology | Hard disk test ‘surprises’ Google

Here is a direct link to the paper itself:  http://216.239.37.132/papers/disk_failures.pdf