Seagate ST9500621NS Computer Drive User Manual


 
16 Constellation.2 Serial ATA Product Manual, Rev. B
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 Imme
-
diate and Idle Immediate also provide a method to directly transition the drive into supported power condi-
tions.
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
S.M.A.R.T. Read Data Reports
Attribute 192 - Emergency Retract Count
Attribute 193 - Load/Unload Cycle Count
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)