Comment 622 for bug 59695

In my opinion, the problem is not in those scripts, nor is it a Dell problem. The problem is the crappy power management in laptop HDDs. I own a Dell D820 with a Hitachi HDD by the way.

I recently had contact with Hitachi technical support on this issue. They advised me to put my HDD APM to setting "Active Idle" (setting 192) using their own Hitachi tool. The Dell bios on my system doesn't even touch the drives APM settings, it is controlled by the HDD firmware settings itself (and can be changed). Setting APM to 192 using the Hitachi Tool is basically the same as executing the 'hdparm -B 192 /de/sda' in Ubuntu, the only difference is that this is now the drives default (which used to be 128).

In my opinion (I have no scientific data to back this up, its just something I observed), the APM, and especially the disk head parking time (the clicking noise is the disk head parking) is set to a Windows timing. What I mean with this is that most of the time (unless you're doing nothing for a long time) Windows is accessing the disk every 4 or 5 seconds, which is too fast for the disk heads to park. However, Linux is much more disk efficient, accessing the disk at a slightly higher interval (say 8 seconds). What happens is that the Linux disk access timing has an idle time which is high enough for the heads to park, and just after they've parked, the disk is accessed again. In my opinion, this is what is causing the LoadCycleCount to increase so rapidly on Ubuntu (and other Linux distro's for that matter).

What would be a good solution is to have a disk head parking time (the idle time needed for the disk heads to park) which is configurable. However, at least on my Hitachi drive, this can't be done. Setting APM to 191 uses the same timing as 128, and 192 switches head parking off completely. There is absolutely no way to control the timing. Another option would be to configure Linux in such a way that it accesses the disk at a much higher rate OR a much lower rate. Either option would be sufficient to solve the problem. The only difference is that with a higher disk access rate, the heads will not park that often (but will park when you're doing nothing at all).