23 Mar
2010
23 Mar
'10
7:45 p.m.
On Tue, Mar 23, 2010 at 07:14:13PM -0500, John Foust wrote:
At 07:06 PM 3/23/2010, Dave McGuire wrote:
Most electronics these days have a pretty large MTBF - usually, by the time
you get anywhere near a significant fraction of the MTBF the equipment
is long obsolete anyway. For instance, one of the hard drives in my machines
has a MTBF of 1.2 _million_ hours, that's about 136 years. Yes, I expect
it to actually fail a bit sooner (it is a MTBF and not a guarantee, after
all), but I don't expect the drive to be in service in 5 years due to being
replaced by a larger one. As it happens, the manufacturer actually gives
5 years of warranty for that one ...
In my experience, on/off cycles kills equipment
much faster than
long "on" times.
Is that biased by the experience of failures that appear when
equipment is powered-on?
One would seem to be shaped by simple MTBF, the other by some
sort of electrical or mechanical surge.
There are several things that kill machines on powerup, among them
- electrical surges
- thermal changes
- for hard drives, especially older ones running for a long time,
stiction (having the heads stick to the platters)
- running out of power cycles
The last one is/was an issue for laptop drives, as they are specified only
for a limited number of powercycles. With very aggressive power management
shutting them down/powering them up every few minutes, that number isn't
as large as one might think.
Regards,
Alex.
--
"Opportunity is missed by most people because it is dressed in overalls and
looks like work." -- Thomas A. Edison