Note: The information contained in this article is structured as help information for the System Management Interface Tool (SMIT) and is not intended for use as a procedural or conceptual article.
Power Management is a technique that enables hardware and software to minimize system power consumption.
Power Management can be enabled or disabled. When Power Management is enabled, each device can enter power saving mode, and the system can change the system state. When Power Management is disabled, the Power Management code is still loaded and running, but the system remains in the full-on state.
You can unconfigure Power Management. When Power Management is unconfigured, the system never performs system state transition and the devices never enter power saving mode. Unconfiguring means that there is no Power Management code running on the system, whereas disabling Power Management means the Power Management code is still loaded and running, but the system remains in the full-on state. You can reconfigure Power Management by rebooting system.
You can configure Power Management. The system automatically performs system state transition and the devices enter power saving mode while Power Management is configured.
You can unconfigure Power Management. The system never performs system state transition and the devices never enter power saving mode if Power Management is unconfigured. Unconfiguring means that there is no Power Management code running on the system, whereas disabling Power Management means the Power Management code is still loaded and running, but the system remains in the full-on state.
You can start system state transitions. Power Management has the following system states.
Specify one of the system states you want to move the system into. Possible settings are: standby, suspend, hibernation, and shutdown.
Changes or displays parameters such as system idle time, action when main power is switched off, limitation of state transition for general users, enable or disable resume password, TTY session handling for suspend or hibernation, and so on.
Sets the system idle time to any value in the range 1 to 120 minutes. Zero system idle time disables system idle time.
Sets the duration of suspend to hibernation. The value should be in the range 1 to 120 minutes. Zero disables the timer for this function.
Set an action for the time system idle timer expiration. When system idle timer expires, the system automatically initiates the power management state transition.
Possible settings are ignore, standby, suspend, hibernation, and shutdown.
Set an action for the time notebook LID is closed. This is valid only on the notebook type machines.
Possible settings are ignore, standby, suspend, hibernation, and shutdown.
Set an action for the time main power switch is pushed. When a user pushes the main power switch, the system initiates the power management state transition.
Possible settings are ignore, standby, suspend, hibernation, and shutdown.
Note: If necessary, you can override the selected state transition and turn off the power immediately by pressing the power button three times quickly (within a two-second period).
Set an action for the time optional battery is low. This is valid only on the notebook type machines.
Possible settings are ignore, suspend, hibernation, and shutdown.
Limits which system state transition a general user can use.
Power management transitions have the following priority:
A general user can start a the specified state transition or state transitions with lower priority. For example, if this field is set to hibernation, then a general user can start standby, suspend, and hibernation, but he cannot start shutdown. If the value is set to none, a general user cannot start any state transitions.
Turns on or off beep for power management. A beep sounds when the system enters the standby, suspend, or hibernation state.
Enables or disables password check at the time of resuming (resume password). Resume password is not available in LFT session.
Enables or disables resuming by ringing via modem (ringing resume).
Specifies LFT session termination at suspend or hibernation.
Possible settings are terminate and continue.
Specifies TTY session termination at suspend or hibernation.
Possible settings are terminate and continue.
Specifies sync daemon (syncd) termination at standby.
Possible settings are terminate and continue.
Power management has two timers for executing system state transition at specified time. The timers are the resume timer and the suspend, hibernation or shutdown timer.
You can change these timer values.
Sets the definition of power saving state used by the suspend, hibernation or shutdown timer.
Possible settings are suspend, hibernation, or shutdown.
Sets time for entering power saving state. To disable timer, enter 0.
The time is specified as a 24-hour, local calendar time and is in YYMMDDHHMM format. Entering only HHMM specifies same time everyday.
For example, specifying
Sets time for resuming. Some Power Management machines do not support this feature for every state (suspend, hibernation, shutdown). To disable the timer, enter 0.
The time is specified as a 24-hour, local calendar time and is in YYMMDDHHMM format. Entering only HHMM specifies same time everyday.
For example, specifying
Display power management system (DPMS) has three values: dim time, suspend time, and turn-off time. You can change these values. Even if power management is unconfigured, DPMS is still available.
Each power-management-aware device has its idle time. When a device expires, it enters the device idle mode to save power consumption. You can change the idle time of each device.
Specifies a device logical name.
Sets the idle time to any value in the range 1 to 120 minutes. Zero idle time disables idle time of the specified device.
You can display information about the battery or discharge the battery.
If the optional battery is loaded on your machine, you can display information about the battery such as battery capacity, remaining capacity, and so on.
If the optional battery is loaded on your machine, you can discharge the battery to prevent memory effect.
Memory Effect:
If you use 50% of a battery's capacity and charge it every time (about 20 to 30 times), then the battery cannot be used at more than 50% of its capacity. This is called the memory effect of battery. If the battery is fully discharged (made empty) and then fully recharged, the battery can be used at 100% again.