Comment 8 for bug 229693

A setting that goes into /proc/sys/vm is just going into system memory, which of course is retained across a suspend. But the hdparm setting is only retained by the hard drive itself, and the hard drives that I'm familiar with seem to clear the setting when they wake from suspend.

I haven't tried moving the hdparm settings into power.d/laptop-tools yet, but I believe by virtue of being in the power.d directory that that script is only meant to be run on power state changes (which is correct given its current contents).

"I suppose that if there are hdparm settings that are specifically executed for each change in power state , EXCEPT for sleep/resume, then it would directly be an acpi/pm-utils bug for simply not including those scripts."

This seems to be the current situation, yes. Sleep/resume is not considered a "change in power state". So the hdparm settings in power.sh are pretty much useless, unless of course you never suspend at all.