Aggressive Link Power Management

<h2 id="description">Description</h2>
<p>When enabled via the AHCI controller, this allows the SATA <a href="/facts/Host_bus_adapter/nQbbDHF2">host bus adapter</a> to enter a low-power state during periods of inactivity, thus saving energy. The drawback to this is increased periodic <a href="/facts/Latency_(engineering)/6Bjhn30H">latency</a> as the drive must be re-activated and brought back on-line before it can be used, and this will often appear as a delay to the end-user.
</p>
<h2 id="states">States</h2>
<p>There are three states:<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a>
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<ul><li><i>Active</i></li>
<li><i>Low Power</i> with two internal states <i>Partial</i> and <i>Slumber</i>. Partial has a maximum return latency of 10 microseconds while slumber has a maximum latency of 10 milliseconds. The states can be initiated by Host (HIPM), Device (DIPM) or both. If SATA <a href="/facts/Hot_swapping/Jn56Jw3h">hot swapping</a> is enabled, this state is unavailable.</li>
<li><i>Device Sleep</i> with a maximum return latency of 20 milliseconds unless otherwise specified in Identify Data Log. If SATA <a href="/facts/Hot_swapping/Jn56Jw3h">hot swapping</a> is enabled, this state is unavailable.</li></ul>
<p>These can be selected by the SATA AHCI driver, usually via a configuration option, or by the OS Power Options. Windows Vista and later allows the tweaking of AHCI LPM modes through a registry hack.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a>
</p>
<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Energy_Star/t4qaxkLq">Energy Star</a></li>
<li><a href="/facts/Green_computing/SpV1lJg2">Green computing</a></li>
<li><a href="/facts/Active_State_Power_Management/FYszGdce">Active State Power Management</a> (ASPM)</li></ul>

<h2 id="external-links">External links</h2>
<ul><li><a href="https://access.redhat.com/knowledge/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Power_Management_Guide/ALPM.html">Aggressive Link Power Management</a> - <a href="/facts/Red_Hat/5rhmBLBa">Red Hat</a></li>
<li><a href="http://www.intel.com/content/dam/doc/reference-guide/sata-devices-implementation-recommendations.pdf">"Designing Energy Efficient SATA Devices"</a> (PDF). - <a href="/facts/Intel/SMF0gJJX">Intel</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>"Serial ATA AHCI: Specification, Rev. 1.3". Intel. Retrieved 31 October 2012. <a href="http://www.intel.com/content/www/us/en/io/serial-ata/serial-ata-ahci-spec-rev1_3.html" target="_blank">http://www.intel.com/content/www/us/en/io/serial-ata/serial-ata-ahci-spec-rev1_3.html</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>"Designing Energy Efficient SATA Devices" (PDF). Intel. Retrieved 31 October 2012. <a href="http://www.intel.com/content/dam/doc/reference-guide/sata-devices-implementation-recommendations.pdf" target="_blank">http://www.intel.com/content/dam/doc/reference-guide/sata-devices-implementation-recommendations.pdf</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>"Add AHCI Link Power Management to Power Options in Windows". 26 July 2017. Retrieved 4 January 2023. <a href="https://www.tenforums.com/tutorials/72971-add-ahci-link-power-management-power-options-windows.html" target="_blank">https://www.tenforums.com/tutorials/72971-add-ahci-link-power-management-power-options-windows.html</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
</ol>

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Aggressive Link Power Management