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__TOC__== AHCI Link Power Management Overview ==AHCI Aggressive Link Power Management (ALPM) is a mechanism where the SATA AHCI controller puts the SATA link to the internal for reducing SSD/HDD and/or power consumption.If ALPM is enabled, SSD disk goes into a very low -power mode when there's SSD has no IO (inputI/output) O activity for a while. The controller automatically puts the link back into active power state when there's real work to be done. This is done to save power consumption by the HDD andOn I/or O request, SSD disk. Tests show that this can save around 0.4 Watts of power and decrease mSATA average temperatureis resumed.* HIPM = Host Initiated Link Power Management* DIPM = Device Initiated Link Power Management
The Link Power Management option is hidden/disabled by default in Windows advanced power options, and it is required to add the support into Windows registry:
# Adding the AHCI Link Power Management ALPM – HIPM/DIPM option to Advanced Power Settings.## Download the [http://fit-pc.com/download/app-notes/ahci-link-power-management/Add_LPM.reg Add_LPM.reg] (Right click and Save as linkas...).
## Right click on the downloaded '''Add_LPM.reg''' file and click on Merge.
## After the success message appears, restart the unit.
# Removing the AHCI Link Power Management ALPM – HIPM/DIPM option from Advanced Power Settings.## Download the [http://fit-pc.com/download/app-notes/ahci-link-power-management/Remove_LPM.reg Remove_LPM.reg] (Right click and Save as linkas...).
## Right click on the downloaded '''Remove_LPM.reg''' file and click on Merge.
## After the success message appears, restart the unit.
# Configuring the AHCI Link Power Management ALPM – HIPM/DIPM option in the Advanced Power Settings.
## Click on the Start button.
## Type Power Options in the Start search box and press Enter.
## In the Plan Settings window, click on the Change advanced power settings.
## In the Advanced Plan Settings click on the Hard disk option and expand it.
## The following settings are responsible on the AHCI Link Power ManagementALPM: :::::* AHCI Link Power Management ALPM – HIPM/DIPM. It will set the Link Power Management policy:
:::::** Active: Neither HIPM or DIPM allowed
:::::** HIPM: HIPM only is allowed
:::::** DIPM: DIPM only is allowed
:::::** Lowest:HIPM, DIPM and DEVSLP are allowed (if DEVSLP is supported by the storage device).
:::::* AHCI Link Power Management ALPM – Adaptive. It will set the period of AHCI link idle time before the link is put in the slumber state when you have HIPM, DIPM, HIPM+DIPM or Lowest set above. It can be set to be from 0 to 300,000 milliseconds. If the Active is set above, then this will have no effect. === Linux ===Enabling and disabling AHCI Link Power Management in Linux:<br>
== Enabling ALPM in Linux ==
* Create text file /etc/pm/power.d/sata_alpm
#!/bin/sh
for i in /sys/class/scsi_host/host*/link_power_management_policy; do
echo min_power > $i
min_power
min_power
* To disable ALPM simply delete file /etc/pm/power.d/sata_alpm
sudo rm /etc/pm/power.d/sata_alpm
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[[category:application notes]]
[[category:products]]
[[category:IPC2]]
