On Sat, 2011-07-02 at 03:03 +0800, Emmanuel Noobadmin wrote: > On 7/1/11, Timothy Murphy <gayleard at eircom.net> wrote: > > It seems to me that it should be possible > > to have a simple, torch-battery operated, system > > which will keep the machine alive long enough > > to make a graceful exit. > > A full-blown UPS would be excessive, I think, > > as I only want the machine to re-boot > > when the current comes back on. > > Like others have suggested, a cheap UPS is the way to go. The problem > with your idea is that you'll need a DC to AC inverter that can handle > the output current required by your server and something to hold the > batteries (you'll need more than one because attempting to draw a huge > current from a normal battery will either kill it or at the very least > cause it to have a shorter than expected capacity) and everything > together, it's probably going to cost more in both money and time to > have this thing. You will also need to have the device signal the OS to shutdown cleanly and be set to reboot when the power comes back on. And once you've added those features, you will have created a UPS -- likely at an expense in time/money that exceeds simply having bought one. Specifically, a 300W UPS can be had for less than $40 -- that's 0.5~4 hours of overtime or side work depending on your job. You are likely to expend a lot more than 4 hours putting your homemade solution together and achieve a far less reliable result. Unless the experience of amateur electrical engineering is what you are craving (it *is* fun) buy a UPS and be done with it -- just read the docs so you fully understand how to make it tell your computer to start shutting down or booting up, etc. They aren't magic and require a little set up to be fully utilized.