Wandering Thoughts archives


A clever trick to deal with students powering off workstations

One of the eternal curses of student Unix labs is students casually turning off workstations the way they turn off other PCs when they're done with them. (A problem made worse by vendors putting glowing power buttons on the front panel of machines, where they become an easy temptation.)

In theory the answer to this is Wake-on-LAN. You probably have at least one inaccessible computer per lab, so run a daemon on that that notices when workstations are down and sends out a WoL packet to get them back up. In practice, WoL requires a fair number of things to be working just right and can be a bunch of work to get going.

Recently a co-worker shared an interesting low-tech solution to the problem. What we care most about is powered-off machines missing out the nightly updates and automatic maintenance (and somewhat having them ready for students in the morning). The simple way to deal with that is to set the PC BIOSes to power the machines on at 2am or so, somewhat before the scheduled nightly stuff starts.

This does nothing to machines that are already on but revives any machine that the students have powered off, and setting it significantly after your labs close means that students won't be around to turn them off again. (If you run 24-hour labs, I suppose you'll just have to hope.)

Also, modern machines with ACPI usually let you control what happens when the front panel power button is pushed. I recommend that you make it reboot the machine; making it do nothing will just encourage the students to reach around behind the machine and yank the power cord. (It is also cheap insurance against the machine actually needing a reboot to get out of some peculiar state.)

sysadmin/WakeupTrick written at 20:51:16; Add Comment

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