dtpower

The Power Management graphical user interface, dtpower, allows you to designate periods of inactivity after which the display will turn off and the system will shut down. You can also use this tool to set the time of day to activate the automatic shutdown; for example, if you wish to use this feature only after your regular work hours.

On sun4u workstations, you can also use dtpower to power on the system at a specific time of day after an autoshutdown through the AutoWakeup feature.

How to use this program on sun4m and sun4u desktop machines is described in Chapter 2, "Using Power Management." If you have a SPARCstation Voyager, refer to Chapter 3, "Using Power Management on SPARCstation Voyager Systems" instead, where additional features unique to that nomadic machine are included.

Suspend-Resume

Suspend-Resume is a new, time-saving feature in the Power Management software that allows you to power cycle your system without losing the state of your current activities. Your workspace and files are preserved when the system is powered off so that they can be restored to the same state when the system is powered on.

For example, you can be in the process of editing a document when you decide to leave and power off your system. By using the Suspend-Resume feature, your edit session is automatically restored and appears in the same state the next time you power on the system.

Suspend-Resume is used automatically when dtpower performs an autoshutdown of your workstation. You also can use these features through the keyboard. The Suspend-Resume features are described in more detail in Chapter 4, "Suspend-Resume."

Choosing to Use Power Management

Powering off a desktop system may interfere with some operations that involve that machine. Take into account the following guidelines before deciding when to use Power Management features on a desktop machine.

Electronic Mail Issues

Mail will not be sent to any mail spool file on a machine while it is suspended. Typically, if mail cannot be delivered for more than three days, it is returned to the sender as undeliverable.

If you suspend your system for three days or longer, and your machine has a local mail spool, you may fail to receive items of mail that have been bounced back to the sender.

Mail Alias Issues

Mail aliases on a machine are not available to other users while that machine is suspended. If the machine is suspended long enough (typically three days), messages sent to an alias on that machine will be bounced back to the sender.

Remote Login Issues

You cannot use rlogin to connect to a machine while that machine is suspended. This command does not cause the machine to resume from a suspended state.

While your machine is suspended, you cannot access it by remote dial in.

Cron Job Issues

Operations specified in a cron file do not run while a machine is suspended.

When the time arrives for a cron job to begin for a machine that is suspended, that job does not run at that time, nor is the job queued up to run later when that machine resumes.

Calendar Manager Issues

Calendar Manager does not display pop-up windows for scheduled events that occur while the desktop machine is suspended.

Thermal Stress Issues

The goal of Power Management is to conserve electricity. However, you should also take into account how an increase in power cycling will affect the overall reliability of the hardware.

Power Management software is active by default on a sun4u systems (such as the Sun Ultra^(TM) 1). Accordingly, the Power Management system for those machines is designed to evaluate each automatic power-cycle request that occurs due to the system being idle. If this evaluation determines that the thermal shock of power cycling on this occasion would contribute to decreasing hardware reliability, then this power-cycle request is deferred.

Despite this feature, you can still choose to turn off a sun4u system manually at any time. This checking feature is intended as a brake on the hardware being subjected to an excessive number of automatic power-cycle requests.