Seagate Exos X20 SATA Product Manual, Rev. B
14
www.seagate.com
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.
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" subcommand 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
Power Condition Name
Power Condition ID
Description
Idle_a
81
H
Reduced electronics
Idle_b
82
H
Heads unloaded. Disks spinning at full RPM
Idle_c
83
H
Heads unloaded. Disks spinning at reduced RPM
Standby_z
00
H
Heads unloaded. Motor stopped (disks not spinning)
