On most distros installations, there is a package “laptop-mode” tools included.
The package is meant to ensure power saving features on laptops.
However, at SGLNX, we discovered that this feature may be sub-controlled by another package that dictates if the “laptop-mode” settings is enabled or disabled.
It started out when we had a problem with hard-drive clicking noises on a recently purchased 320gb hdd to replace a lower capacity hdd within a working laptop. In our fact-finding mission to find out the root causes, we discovered that it was a hdd setting that could be controlled via the command “hdparm“.
The hard-drive clicking noises was made by the parking of the heads of the hdd when it detected an idle period of a certain amount of time. To prevent the parking of the heads, the command “sudo hdparm -B 255 /dev/sda” was issued and it got rid of the parking/click noises from the hdd. Further research into the topic gave light to having the settings to be pre-set on boot by means of the “laptop-mode” package.
To automatically configure the hdparm settings upon boot, the configuration file of the laptop-mode package ( /etc/laptop-mode/laptop-mode.conf ) has to be edited manually.
#
# Power management for HD (hdparm -B values)
#
BATT_HD_POWERMGMT=1
LM_AC_HD_POWERMGMT=254
NOLM_AC_HD_POWERMGMT=254
The values above had to be changed to “255″ for all 3 lines to turn off Advance Power Management on the hdd and thus eliminating the hdd clicking noises.
However, upon changing it and executing the start/stop script via “sudo /etc/init.d/laptop-mode restart”
The values did not stick when we displayed the current hdparm setting “sudo hdparm -I /dev/sda“. Only then it was realized that laptop-mode was not running at all with the command “cat /proc/sys/vm/laptop-mode“. It was then discovered that another package was dictating whether laptop-mode should be started upon boot.
The package “acpi-support” was actually preventing “laptop-mode” to be started at all during the boot process.
To ensure that laptop-mode starts during the boot process, a little tweaking is needed on the configuration files of “acpi-support”.
sudo gedit /etc/default/acpi-support
Find the line that says
ENABLE_LAPTOP_MODE = False
Change the “false” to “true”.
Save and quit the editor.
Enter terminal and do a
sudo /etc/init.d/laptop-mode restart
With the above instructions, we were able to make the hdparm settings stick and you will be able to make use of laptop-mode and make the laptop last longer on battery……. And we certainly hope so!
The above illustrates our experience encountered with laptop-mode tools in Ubuntu Karmic Koala 9.10. The commands and configuration file locations may vary for your linux distros.
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Tags: acpi, acpi-support, apm, battery, config, Distro, hdd, hdd clicks, hdd noises, hdparm, laptop, laptop-mode, last longer, lasting, longer, parking heads, power, power management, save power, settings, ubuntu