Hitachi IC25N040ATCS04-0 - Travelstar 40GN 40GB UDMA/100 4200RPM 2MB 2.5" IDE Hard Drive Specifications page 96

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 recent behavior of the user. It is
not possible to achieve the same level of Power savings with a fixed entry time into Active Idle because
every user's 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 needs more recovery time switching from this mode to Active mode.
Hitachi Travelstar 60GH & 40GN hard disk drive specifications
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