Hitachi HTS541660J9SA00 Interface Power Management Mode Slumber and Partial, Active Idle mode

Travelstar 5K160 (SATA) Hard Disk Drive Specification

The Advanced Power Management feature is independent of the Standby timer setting. If both Advanced Power Management level and the Standby timer are set, the device will go to the Standby state when the timer times out or the device’s Advanced Power Management algorithm indicates that it is time to enter the Standby state.

The IDENTIFY DEVICE response word 83, bit 3 indicates that Advanced Power Management feature is supported if set. Word 86, bit 3 indicates that Advanced Power Management is enabled if set.

Word 91, bits 7-0 contain the current Advanced Power Management level if Advanced Power Management is enabled.

12.6.1Performance Idle mode

This mode is usually entered immediately after Active mode command processing is complete, instead of conventional idle mode. In Performance Idle mode, all electronic components remain powered and full frequency servo remains operational. This provides instantaneous response to the next command. The duration of this mode is intelligently managed as described below.

12.6.2Active Idle mode

In this mode, power consumption is 45-55% less than that of Performance Idle mode. Additional electronics are powered off, and the head is parked near the mid-diameter of the disk without servoing. Recovery time to Active mode is about 20ms.

12.6.3Low Power Idle mode

Power consumption is 60%-65% less than that of Performance Idle mode. The heads are unloaded on the ramp, however the spindle is still rotated at the full speed. Recovery time to Active mode is about 300ms.

12.6.4Transition Time

The transition time is dynamically managed by users recent access pattern, instead of fixed times. The ABLE-3 algorithm monitors the interval between commands instead of the command frequency of ABLE-2. The algorithm supposes that next command will come with the same command interval distribution as the previous access pattern. The algorithm calculates the expected average saving energy and response delay for next command in several transition time case based on this assumption. And it selects the most effective transition time with the condition that the calculated response delay is shorter than the value calculated from the specified level by Set Feature Enable Advanced Power Management command.

The optimal time to enter Active Idle mode is variable depending on the users recent behavior. It is not possible to achieve the same level of Power savings with a fixed entry time into Active Idle because every users data and access pattern is different. The optimum entry time changes over time.

The same algorithm works for entering into Low Power Idle mode and Standby mode, which consumes less power but need more recovery time switching from this mode to Active mode.

12.7 Interface Power Management Mode (Slumber and Partial)

Interface Power Management Mode is supported by both Device-initiated interface power management and Host-initiated interface power management. Please refer to the Serial ATA Specification about Power Management Mode.

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