Checking an HD for problems
Apparently, though unproven, at 23:00 on Wednesday 22 September 2010, walt did
> On 09/22/2010 01:26 PM, Stroller wrote:
> > On 22 Sep 2010, at 17:46, Grant wrote:
> >> ... I noticed some errors when I was cp -ax'ing everything
> >> from my old drive to the new drive which were accompanied by loud
> >> clicks. Is there a way to do a comprehensive test/check of the old
> >> drive to see if it has any problems?
> > You don't need to do a test. The disk that is making the noises is
> > f**ked.
> > Assuming that it's the old drive that is knackered...
> I was thinking the same. In the past three or four years I've had more
> brand new drives go bad than older ones. Funny, though, the replacement
> drives I've received under warranty work spectacularly well. Just luck?
No, not luck. It's a numbers game and that how the dice roll.
Modern drives are complex. As such they are more likely to fail than ancient
drives simply because of the complexity. They are also better engineered than
old ones but the loss from complexity is greater than the game from better
engineering. Plus, they are incredibly cheap compared to ancient times.
Engineered products all have characteristic failure rates common across the
model, the infamous bathtub curve. The factory can't do the full range of
nurn-in tests they'd like to (bean counters rule), so you get a drive at the
later end of the bathtub. Hence, you see elevated failure rates. The factory
is willing to take a financial knock here as the loss from a few replacements
is much lower than the gigantic loss from fully and properly testing every
drive for hours and hours.
You get a replacement. Simple odds are that it is not one of the few that will
fail early, so it doesn't and you think "Wow! The gods like me." Nope,
statistics like me.
If the factory was real smart, they would keep a small stock of fully tested
drives on the replacement shelf, only to be released as under-warranty
replacements. You'd be certain these drives would NOT fail and it's trivially
easy to get this past the bean counters because you'd be winning back customer
loyalty. And the cost of testing those few drives fully is not that much. The
average bean counter has a ballistic orgasm at the thought of this, and yes
they can even tell you the price they attach to winning back that loyalty.
So now you know. Accountants do not think like techies.
alan dot mckinnon at gmail dot com