to Bart Samwel :

Thanks for all your help in solving this problem. Having acpi-support
setting some sane apm default while on battery and 254 while on AC would
be a big help to solve this problem.

Possible problems with a default apm of 128 while on battery :
* some people might use their laptops *a lot* on battery. People who use their 
laptops for 9 hours a day and are seeing a Load_Cycle_Count increase of more 60 
per hour will reach 600.000 Load_Cycles within three years of usage. The amount 
of people who would use their laptop for 9 hours each day are probably a very 
small minority. Using the laptop on battery for more than 9 hours a day 
increases the risk of bumps *a lot* which would make using apm 254 a sure 
harddrive killer. Their battery would probably be dead way before their 
harddrive dies. Some of these people might also prefer flash disks which don't 
have moving parts.
* Some users would use their laptop on battery for four hours each day. They 
would have a problem if their Load_Cycle_Count would increase with more than 
136 per hour.
* If most people would run on battery for seven hours a week they would be able 
to handle 549 Load_Cycles per hour and still not reach 600.000 Load_Cycles 
within three years of usage. 
* some people already have a really high Load_Cycle_Count because they have 
been using aggressive power management defaults set by their harddrive even 
while on AC. They would have to manually override this number of 128.

Possible problems with a default apm of 254 while on battery : 
* no protection from bumps making it more likely for the harddrive to die from 
an accidental bump. The more you use your laptop on battery the higher the risk 
of death by bump.
* more power usage

Maybe some value between 128 and 254 works better for running on
battery. The problem is that apm values between 128 and 254 are
different for each harddrive and might even turn off head parking for
some drives (as I understand it). If an apm of 253 would guarantee a
"low amount of head parking but still do some headparking" that might be
a more sane default for running on battery but as far as I know it
doesn't (but I'm not an expert).

IMHO all of this makes very clear that reducing unnecessary disk
activity is also very important.

-- 
High frequency of load/unload cycles on some hard disks may shorten lifetime
https://bugs.launchpad.net/bugs/59695
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