Highly erratic
Individual drives from a good production run are also unpredictable. What I tell my clients is: "On average they probably run between 5 and 10 years, but that doesn't mean your hard disk isn't going to fail in 10 minutes".
I haven't seen a head crash for quite a few years, and shaft chatter isn't anything like the problem it once was, nor is sticky heads.
Most of the failures I see are sudden and catostrophic (no data recovery possible outside a $ cleanroom data recovery house $). Most common is failed head circuits (can't find track 0). Commonly this is not on the main logic board, because swapping the board doesn't fix the problem. Second most common is motor electronics (doesn't spin). Broken positioning mechanisms were a problem a few years ago, but I haven't seen that lately. Following far behind is failed video cards (they can take just about everything else with them) and then a bit of everything.
Most common client comments are:
- "Backup? yes, we have one from about 8 months ago, but I'm not sure I can find it. Can't we get it off the hard disk some how?"
- "But it worked just fine all day yesterday. Why would it just stop working?"
- "I was just saving a file and this error message popped up. How could it just do that?"
- "I thought this was a good brand?"
- "Three thousand dollars to get the data off? Well, my son says he knows somebody who's and expert and will do it for free."