Synchronizing shutdown of several computers on one UPS

Question

With a single computer working from a UPS, a power outage would result in the computer shutting down, followed by the UPS shutting down. The UPS would then not supply power to its outputs.

With a USB based UPS, you can set up a machine as a server to broadcast the UPS status to other machines.

But, with several computers on one UPS, how do you manage shutdown? You don't want the UPS to shut down before all the attached computers shut down as this may damage the computer. (By leaving incomplete anything being written to disk.)

The alternative would be to not shut down the UPS and each computer is left to it's own devices to shutdown prior to the battery running out.

Or is there some other scheme used when several computers are on one UPS?

Answer 1

Common problem in computer-rooms.

In larger deployments you usually have a UPS with a LAN -interface that can broadcast the shutdown to other computers.
In smaller setups with a USB connected UPS the computer that is directly connected is responsible to sending the message to the others.
Most UPS monitor software has features for both scenarios.
(APC PowerChute or the open source NUT. Just to name 2 of the more well-known software packages.)

You determine what is the longest shutdown-time among all computers/devices. You add some safety margin to that (3-5 minutes) and you configure the UPS (or the monitoring computer) to send out the "shutdown now!" command to everyone that many minutes prior to the USP battery being completely depleted.
That should give everybody time enough to be safely shut down.

Obviously you will have to have the network equipment on the UPS too.

E.g Say you find that the slowest systems need about 5 minutes to shutdown. + 5 minutes safety-margin = 10 minutes.
So the shutdown command is send out 10 minutes before the UPS is really empty.

P.S. You DON'T want to go to shutdown immediately when the UPS switches to battery power, because chances are it is just a short spike and normal power is back in a few seconds.
And typical outage patterns in your locality may also determine exactly how you schedule things.
(I once had to setup a deployment were each day at 21:00 the power-grid would go unstable for 5 to 10 minutes. Pottery factory next door that fired up a large kiln every night at 21:00. This would cause our UPS to kick in for a couple of seconds several times between 21:00 and 21:10.)

Answer 2

A manual for your version of PowerChute would help, but it seems that it has a mechanism for defining user command files for execution for events such as shutdown.

The random PowerChute manual that I found specified that such files need to be stored in C:\Program Files (x86)\APC\PowerChute ... Edition\agent\cmdfiles, but may not apply to your version.

You could use in your script the free psshutdown utility that can shutdown remote computers on the network, in order to turn off the other computers on your local network.

The script can be tested before, then installed on the computer that has PowerChute installed. I suggest testing the concept, by manually cutting power to the APC, to ensure that the script has enough time to complete its work.

If your version of PowerChute does not support the shutdown event handler, you can instead create a shutdown script for the Windows computer. See Working with startup, shutdown, logon, and logoff scripts using the Local Group Policy Editor .