Let’s Talk about Hard Drives

Posted: August 27th, 2011 | Author: | Filed under: Advice (Unsolicited), Computers | Comments Off

Last week, one of my external drives failed, and another indicated that it’s about to die by failing a read and causing my RAID volume to degrade. Neither of these failures were surprising; both drives were well outside of their warranty periods. The way these drives failed and the (sadly ongoing) quest to replace them has brought up a couple of things that I’ll talk about here.

Failed drives means shopping for replacements. When it comes to external hard drives, we seem to be presented with a multitude of choices, none of which are good. Judging by reviews on NewEgg, external consumer-grade hard drives are some combination of:

  • Unreliable
  • Slow
  • Feature-poor
  • Plagued with awful customer support

I was surprised at how many of the one- and two-star reviews for hard drives on NewEgg (and virtually everywhere else that sells drives) display some of the same common misconceptions. It’s a sad indicator that as an industry, we still haven’t figured out how to make computers anything less than magical and inscrutable to the average consumer. I’m going to lay out a couple of those misconceptions in the next couple of posts. They’ve doubtlessly been rehashed elsewhere, but these are things that deserve repeating.

The Bathtub Curve

If you were to plot failure rate of hard drives versus time on a graph, the graph would probably look like the blue line in the graph below (thanks, Wikipedia!):

The Notorious Bathtub Curve, Image Courtesy of Wikipedia

This blue line is what’s referred to in reliability engineering as a bathtub curve, because its shape is evocative of a bathtub. In plain English, the bathtub curve basically says

  • Things that are shipped with defects usually fail early.
  • Things that work as designed still eventually wear out.
  • In the middle, anything can happen, but failure is less likely.

Many one-star NewEgg reviews I came across were some variant of:

Drive fails after X days of use. What a piece of crap. I’m never buying from this company again.

These are people who have unfortunately hit the wrong end of the bathtub curve.

Why does this happen? Well, some of it has to do with manufacturing; with something this intricate there will inevitably be defects, regardless of how much quality assurance you put into it. Some of it might have to do with what happens to the drives during shipping. Sometimes there is actually a systemic defect in a particular model or production batch that goes undetected by quality assurance; this usually results in a class action lawsuit months or years down the road.

The best bet, as I’ve stated here several times in the past, is to never assume that the drive will last another day. I was shocked at the number of times I read a review like this:

Bought this drive and it died three days later. Now 50,000 photos of my cat Muffins are gone. I hate you, Seagate, and so does Muffins.

So you bought this drive, and copied your photos to it, and then … you deleted the originals?! I’ve said it before and I’ll say it again: if there’s only one copy, it is only a matter of time before you lose that data.

Next week: why the replacement for your failed drive is more likely to fail, and why hard drive manufacturers are lying to you.