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Drive specifications
2.5.4
Extended Power Conditions - PowerChoice™
Utilizing the load/unload architecture a programmable power management interface is provided to tailor systems for
reduced power consumption and performance requirements.
The table below lists the supported power conditions available in PowerChoice. Power conditions are ordered from highest
power consumption (and shortest recovery time) to lowest power consumption (and longest recovery time) as follows:
Idle_a power >= Idle_b power >= Idle_c power >= Standby_z power. The further users go down in the table, the more
power savings is actualized. For example, Idle_b results in greater power savings than the Idle_a power condition. Standby
results in the greatest power savings.
Power Condition Name
Power Condition ID
Description
Idle_a
81H
Reduced electronics
Idle_b
82H
Heads unloaded. Disks spinning at full RPM
Idle_c
83H
Heads unloaded. Disks spinning at reduced RPM
Standby_z
00H
Heads unloaded. Motor stopped (disks not spinning)
Each power condition has a set of current, saved and default settings. Default settings are not modifiable. Default and
saved settings persist across power-on resets. The current settings do not persist across power-on resets. At the time of
manufacture, the default, saved and current settings are in the Power Conditions log match.
PowerChoice is invoked using one of two methods
•
Automatic power transitions which are triggered by expiration of individual power condition timers. These timer values may be
customized and enabled using the Extended Power Conditions (EPC) feature set using the standardized Set Features command
interface.
•
Immediate host commanded power transitions may be initiated using an EPC Set Features "Go to Power Condition" subcom-
mand to enter any supported power condition. Legacy power commands Standby Immediate and Idle Immediate also provide a
method to directly transition the drive into supported power conditions.
PowerChoice exits power saving states under the following conditions
•
Any command which requires the drive to enter the PM0: Active state (media access)
•
Power on reset
PowerChoice provides the following reporting methods for tracking purposes
Check Power Mode Command
•
Reports the current power state of the drive
Identify Device Command
•
EPC Feature set supported flag
•
EPC Feature enabled flag is set if at least one Idle power condition timer is enabled
Power Condition Log reports the following for each power condition
•
Nominal recovery time from the power condition to active
•
If the power condition is Supported, Changeable, and Savable
•
Default enabled state, and timer value
•
Saved enabled state, and timer value
•
Current enabled state, and timer value
Seagate Exos X24 SATA Product Manual, Rev. C
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