However, powering down a rotational drive too aggressively can result in excessive wear on the drive’s mechanical parts. The device needs to be powered down more aggressively when in Modern Standby in order to meet the system’s power requirements.
Now that SATA drives with rotational media are supported on Modern Standby systems, there is a need to balance power savings with device reliability. As mentioned above, this implies that HIPM must be supported. Note that if the controller has specified that DEVSLP must be entered from Slumber, StorAHCI will first transition to Slumber and then upon completing the transition to Slumber it will immediately transition to DEVSLP. The following table shows the time the SATA device must be idle before it transitions to DEVSLP under different system power states. “Aggressive DEVSLP” per the SATA-I/O spec.).ĭEVSLP is mapped to a single logical idle power state or “F-State,” namely F1. Thus, StorAHCI does not use the hardware-controlled DEVSLP feature (a.k.a.
StorAHCI controls DEVSLP directly in order to effectively balance power, responsiveness, and diagnosability.
Thus, StorAHCI also needs to control transitions to Slumber. HIPM-only was chosen because StorAHCI controls DEVSLP transitions directly and typically DEVSLP-capable controllers indicate that DEVSLP can only be reached through the Slumber state. StorAHCI allows the controller to handle transitions from Active to Partial by enabling the “Aggressive Partial feature” of the SATA-I/O standard.Īfter the device enters D3, StorAHCI will immediately transition the link to Slumber. When the device is in D0, after the link has been in Partial for 100ms, StorAHCI will transition to Slumber. HIPM/DIPMīy default, HIPM-only is enabled and StorAHCI manages Partial to Slumber transitions. This section details how Microsoft’s in-box SATA driver (StorAHCI) manages power and what configuration options are available.
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