Hard Disk Life and Luck

Recent research conducted by the Carnegie Mellon University and Google have shown that disk drives can die at any time without warning. While most vendors won’t think twice about reciting ‘Ode to a Hard Disk,’ there might be more to it than meets the eye.

Vendor statistics, for example, are based on accelerated testing, which basically means running them at high loads at a higher-than-normal temperature. This method doesn’t seem entirely foolproof because:

1. Normal consumers just don’t use hard drives that way. My own machine manages to stay moderately cool and doesn’t run HD-intensive tasks very often, even though it’s on all the time.
2. The self monitoring and reporting systems built into hard drives have shown less-than-satisfactory performance, with a most failed disks reporting “no trouble found” during vendor/manufacturer tests.

So, what’re the most common factors concerning hard drive life? How about, in no particular order: drive age, general handling, and statistical variations? Now, we’re more or less familiar with age and handling, but what are statistical variations?

Google and CMU looked at 100,000 drives each in their studies. Most of us have very small sample sizes and don’t keep very good records. But the data shows that drives fail for no apparent reason at all ages and in all environments.

That didn’t make things significantly clearer for me, but at 3:40 AM, little makes sense, anyway.

Here’re some more interesting nuggets of info:

• Enterprise drives are no more reliable than consumer drives. The extra money seems to go for margin and warranty costs. These are mass-produced products. There is no secret to making a disk last 3x.
• SMART drive status reporting is pretty useless. If SMART is telling you there is a problem, there probably is a problem. But if it reports no problem, that means nothing.
• Workload has no effect on drive life. So use it all you want. Google did find that a heavy workload increases infant mortality, so when you install a new drive work it hard so you can replace it while it is still economic to do so.
• Ambient temperature has very little effect on drive life until it gets up over 104 F. or 40 C. Even then the effect is slight.

Source: ZDnet blogs.