Device and Bus Power Management: Serial ATA

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Related Specifications

There are currently two sub-projects underway in the SATA subsystem.

  • Asynchronous Notification for ATAPI devices
  • Aggressive Link Power Management (ALPM)

Asynchronous Notification for ATAPI devices


Asynchronous Notification (AN) for SATA ATAPI devices is defined in SATA 2.5 and AHCI 1.1 and higher. Currently in Linux, user space must wake the kernel frequently to check for new media, which causes the CPU to consume unnecessary power. Drives which support this feature will send a notification when new media is inserted and removed, preventing the need to poll for new media.

Aggressive Link Power Management (ALPM)


This feature is described in detail in the AHCI 1.x spec. ALPM is a power-saving technique that focuses on the SATA link. When enabled, it allows the host controller and the disk to negotiate when to lower the power of the SATA link. When it is enabled, it can provide power savings of anywhere from .5-1.5 Watts per disk, depending on the system.

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