[CentOS] A problem with power outages

Sun Mar 25 18:39:12 UTC 2012
Timothy Murphy <gayleard at alice.it>

Ryan Wagoner wrote:

> Additionally if your computer BIOS supports configuring the AC recovery
> power mode to always on, the computer will start back up. Most default to
> last state, which doesn't work as well since shutting down will power off
> the computer, which means that last state is off. There are some
> workarounds to change the shutdown sequence to just halt and not power

Thanks again for your response.
I did an experiment which I probably should have done before,
to find out exactly what happens if the power is cut off, and then restored.
You were completely correct.

My server is an HP MicroServer (running CentOS-6.2).
If the machine was running before being cut off
then it reboots normally when power is restored.
If however it is shutdown before the power is cut
then it does not reboot when power is restored.
As you say, it always returns to the state it was in when the outage occurs.

I looked in the BIOS, but there is no option on this machine
to change that.

So I shall know what to do when I get a UPS.
If there is no better setting I can just allow the UPS to become exhausted
if the outage lasts longer than the life of the UPS.

Timothy Murphy  
e-mail: gayleard /at/ eircom.net
tel: +353-86-2336090, +353-1-2842366
s-mail: School of Mathematics, Trinity College Dublin