One of the most important things for the energy saving on a notebook (but also for the protection of data in special cases such as a stroke due to an accidental fall to the ground) is to put "to rest" the hard disk if it is not used for a given time. However, the excessive use of this function leads to a continuous turn on/off of the hard disk, resulting in premature mechanical death. So we have to find a compromise between energy saving and safeguarding the mechanics of the disk.
The factory settings for most of the notebook HDs are very aggressive and tend to turn off the drive too early and too often for maximum energy saving, so it's usually the operating system to manage this task. Ubuntu (for various and valid reasons) does not change the default factory settings on the disk, but fortunately it's easy to solve this problem.
Open the file /etc/default/acpi-support
in your favourite editor and change the line
Now the energy saving is managed properly.
If you want, you can change the default laptop-mode settings in /etc/laptop-mode/laptop-mode.conf
Since the NC10 has a 6-cell battery that lasts for a very long time, I preferred to change the lines
in order to have better disk performance when working with the battery, sacrificing a little of the power saving.
The TIMEOUT options set to 300 seconds (5 minutes) the standby timeout for the disk.
The POWERMGMT option sets the disk power management, and it can have a value between 1 and 255. A low value results in a better energy saving but less disk performance, an high value results in disk performance but less energy saving.
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