hard disk power down (was: Re: PowerTOP tool released; time to fix the wasted laptop power on fedora?)

[Ville Skyttä]

On Sunday 13 May 2007, Richard Hughes wrote:
> On Sun, 2007-05-13 at 19:24 +0200, Thorsten Leemhuis wrote:
>
> > Just wondering: does Fedora spin down the hard disk by default? It
> > doesn't afaics and it's not easily user-configurable either afaik.
>
> It doesn't - you have to be very careful with the amount of power it
> takes to spin-up a drive (often significant) compared to the amount of
> time it's spun down.

In addition to power consumption, noise may be important in some setups.

> The amount of disk accesses is indeed horrific in a modern distro, and
> the drive doesn't usually spin down for long, even with laptop-mode
> flushing. This is bad.

A bit off topic, but I'm currently (ab?)using FC6's read only root/temporary 
state config in my PVR point get the "unwanted" reads and writes to a tmpfs, 
and persist those files back on disk at shutdown.  The implementation is not 
too pretty and is applicable to a fairly limited set of scenarios, but has 
worked well for me.  Anyway it'd be nice to have something like that in the 
distro so it'd be likely less fragile.  More details and a RFE at 
https://bugzilla.redhat.com/223722