I propose a few things that would prevent Ubuntu from waking up a system which has spun down its disk, and generally should not be using a lot of power. This is an issue because many times the crontab will wake up the disk, swappiness will wake up the disk, and coming out of the lower power state will take forever if all your apps are swapped out (which is common).
This lower power "state" should be enabled when the laptop is on battery power and in use, or the system has not had kb/mouse in put for a while on battery. Maybe create two separate states for each case if need be.
1) Turn swappiness to 0, or disable the swap file/partition completely. This would go a long way to reduce disk IO on modern laptops, which saves battery life and disk life and heat.
2) disable the crontab, or have a separate crontab file with critical jobs and one with non-critical jobs (or 2 sections in the same file). This would allow noncritical cron jobs to be postponed until the disk spins back up. It will also prevent updatedb from happening while the disk is spun down.
3) disable most other background processes which are not critical and might cause the system to wake up the disk
When the system is in use (ie, there is kb/mouse input) then other things should happen:
1) non-critical cron tabs should be postponed until the system is no longer in use
2) swappiness should be decreased to 0 (or be very low) to give better responsiveness on the desktop.
nowadays, laptops come standard issue with 2GB ram, 1GB on ultra low end laptops. There is no reason that the kernel should be swapping your web browser and all of GNOME or KDE out to disk just because updatedb ran in the background. It is unacceptable.
Please give your feedback in the comments section. This is just a rough idea and I haven't thought up all the different tweaks yet.
