[ltp] Re: T420s HD life and Load Cycle counter

Stefan Monnier linux-thinkpad@linux-thinkpad.org
Sun, 03 Jul 2011 10:42:46 -0400


>> Laoptop (and low power desktop drives) are designed to do such "load
>> cycle" *very* often.  This number is unrelated to the number of
> 100k to 300k cycles over the entire drive lifetime on the lesser devices,
> 600k on the good stuff like Hitachi HDDs.  You can kill a heavy drive in a

Last I checked, the limit on "load cycle count" is never mentioned in
specs, whereas the limit on spin-up/spin-down count (aka
Start_Stop_Count) is and is indeed around 600k for many laptop drives.

But admittedly, the specs are rarely very clear about this (e.g. the
spec of my old desktop Seagate drive says "50K start stop cycles",
whereas the specs of my laptop Seagate drive says 600k "load/unload
cycles"), but if you consider the fact that load_cycle_count will always
be at least as large as start_stop_cycle (and often much larger) and
that there is very little in terms of controlling head unload behavior
compared to the precise control over spin-up spin-down, the real meaning
is usually clear.

>> spin-up/spin-down; and other than FUD, there's no evidence that high
>> numbers are a sign of problems to come.  Many manufacturers have simply
> Head unloading slowly degrades the head support integrity, due to flex.
> You can actually hear when the drive does it, btw: a very soft "click".

You can hear it on some drives and not on others.  The fact that you can
hear it doesn't imply any kind of "evidence that high numbers are a sign
of problems to come".

> Which ones, so that I can avoid them like the plague?
> Unloading heads is important for two reasons: unloaded heads are far less
> succeptible to damage due to sudden impacts to the drive, and allow for the
> linear head assembly positioning motor to be either turned off, or operated
> in reduced current.
> So, it reduces idle power consumption of the drive, which is of paramount
> importance for the vendor's marketing department since everyone overstates
> their battery longevity numbers.  It can also decrease the chance of a
> damaged drive that needs to be returned in warrany on the cheap-o crap 1yr
> warranty service.
> Removing Load Cycle Count is just unethical.

Why?  Why would it be unethical to stop telling users how many times the
head was loaded/unloaded?


        Stefan