A.10. Advanced Power Management

APM allows control of the power from software. This can be a blessing and a curse.

The blessing is that the machine can be cleanly and totally shut down remotely. You may want to do this if the remote site is maintaining their power supply.

The curse is that once powered down the machine will not start up again until the Power button is physically pressed. Some machines have a BIOS or motherboard setting to defeat this unhelpful behaviour.

CautionErrors when typing shutdown are worse with APM

Be careful not to confuse shutdown -r now, which cleanly reboots the machine, with shutdown -h now, which cleanly powers down the machine. Someone will need to physically press the Power button if you choose wrongly.

If you are serious about remote site computing then you should investigate remote power switches from companies like Western Telematic, Server Technology and many others. Some models include built-in terminal servers, built-in modems and RS-232 lines to simulate a UPS input power failure (and thus shut the Linux system down cleanly before removing power).