Power Management Commands; Standby Timer; Power Management Feature; Power Mode - Hitachi HDS723020BLA642 Specifications

9.4

Power Management Feature

The power management feature set permits a host to modify the behavior in a manner which reduces the power
required to operate. The power management feature set provides a set of commands and a timer that enables a
device to implement low power consumption modes.
HDS7230xxBLA642 / HDS5C30xxALA632 / HCS5C20xxALA632 implement the following set of functions.
1. A Standby timer
2. Idle command
3. Idle Immediate command
4. Sleep command
5. Standby command
6. Standby Immediate command
9.4.1

Power Mode

The lowest power consumption when the device is powered on occurs in Sleep Mode. When in sleep mode, the
device requires a reset to be activated.
In Standby Mode the device interface is capable of accepting commands, but as the media may not immediately
accessible, there is a delay while waiting for the spindle to reach operating speed.
In Idle Mode the device is capable of responding immediately to media access requests.
In Active Mode the device is under executing a command or accessing the disk media with read look-ahead
function or writes cache function.
9.4.2

Power Management Commands

The Check Power Mode command allows a host to determine if a device is currently in, going to or leaving
standby mode.
The Idle and Idle Immediate commands move a device to idle mode immediately from the active or standby
modes. The idle command also sets the standby timer count and starts the standby timer.
The Standby and Standby Immediate commands move a device to standby mode immediately from the active or
idle modes. The standby command also sets the standby timer count.
The Sleep command moves a device to sleep mode. The device's interface becomes inactive at the completion
of the sleep command. A reset is required to move a device out of sleep mode. When a device exits sleep mode
it will enter Standby mode.
9.4.3

Standby timer

The standby timer provides a method for the device to automatically enter standby mode from either active or
idle mode following a host programmed period of inactivity. If the device is in the active or idle mode, the device
waits for the specified time period and if no command is received, the device automatically enters the standby
mode.
If the value of SECTOR COUNT register on Idle command or Standby command is set to 00h, the standby timer
is disabled.
Hitachi hard disk drive specifications
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