Power Save; Power Save Mode - Fujitsu MHW2120BK Maintenance Manual

Operations

6.2 Power Save

The host can change the power consumption state of the device by issuing a power
command to the device.

6.2.1 Power save mode

There are five types of power consumption state of the device including active
mode where all circuits are active.
• Active mode
•
Active idle mode
•
Low power idle mode
• Standby mode
•
Sleep mode
The device enters the active idle mode by itself. The device also enters the idle
mode in the same way after power-on sequence is completed. The subsequent
mode transition changes depending on the APM setting.
(1) Active mode
In this mode, all the electric circuit in the device are active or the device is under
seek, read or write operation.
A device enters the active mode under the following conditions:
• The media access system is received.
(2) Active idle mode
In this mode, circuits on the device is set to power save mode.
The device enters the Active idle mode under the following conditions:
• After completion of the command execution other than SLEEP and STANDBY
commands.
(3) Low power idle mode
Sets circuits on the device to the power save mode. The heads are disabled in the
safe state.
The device enters the low power mode under the following conditions:
• After certain amount of time has elapsed in the active idle state
(APM Mode 0, Mode 1 and Mode 2)
•
Upon completion of the power-on sequence
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