Aggressive Link Power Management

Aggressive Link Power Management (ALPM) is a power management protocol for Advanced Host Controller Interface-compliant (AHCI) Serial ATA (SATA) devices, such as hard disk drives and solid-state drives.^[1]

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:^[2]

• 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.
• 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.

See also

• Energy Star
• Green computing

References

1. "Serial ATA AHCI: Specification, Rev. 1.3". Intel. Retrieved 31 October 2012.
2. "Designing Energy Efficient SATA Devices" (PDF). Intel. Retrieved 31 October 2012.

External links

• Aggressive Link Power Management - Red Hat
• "Designing Energy Efficient SATA Devices" (PDF). - Intel