Description
When enabled via the AHCI controller, this allows the SATA host bus adapter to enter a low-power state during periods of inactivity, thus saving energy. The drawback to this is increased periodic latency 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.States
There are three states: * ''Active'' * ''Low Power'' with two internal states ''Partial'' and ''Slumber''. 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. Hot swapping is disabled. * ''Device Sleep'' with a maximum return latency of 20 milliseconds unless otherwise specified in Identify Data Log 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. Hot swapping is disabled.See also
* Energy Star * Green computing * Active State Power Management (ASPM)References
External links