Hi, On Tue, 2008-02-12 at 09:50 -0500, Lon Hohberger wrote: > On Fri, 2008-02-08 at 15:32 +0000, gordan@xxxxxxxxxx wrote: > > > I just had another thought. Most motherboards these days are ATX, which > > means ATX type "short-pins-to-power-on" power switches. That means that as > > a _REALLY_ cheap solution I could just get something like a small relay > > switch and wire it into the serial port. When a pin on RS232 goes high > > (e.g. DTR), it activates the switch. I think it would be pretty reliable, > > and the total cost of components would be pennies. The fence agent would > > also be a total of about 10 lines of code, too. :) > > It'd have to be a 'press-and-hold' sort of thing. E.g. either activate > or deactivate DTR for 5+ seconds. ;) > I did something similar in the early days of Sistina. I used a (ISA bus!) lab card with 12 relays on it, one of which was connected across the reset switch of my test machine. Together with a serial console that gave me all the control that I generally needed when working remotely. Its relatively unlikely that an RS-232 port would supply enough current to drive a relay directly, but you might find a suitable alternative in an opto-isolator, and that would also have the advantage of not being inductive and thus it won't potentially put a surge onto your power-rails in case your decoupling isn't 100%. Its also cheaper. Steve. -- Linux-cluster mailing list Linux-cluster@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cluster
