UPS won't shutdown during a power failure

[toolbox_apc]

This was originally posted on APC forums on 2/8/2011

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Hi,

I just noticed recently that my shutdown procedures are not working properly with my UPS. Model is a Smart-UPS 2200 RM XL with the network management card installed.

I have the low battery duration set for 5 minutes. The Shutdown delay is set to 5 minutes. So based on this, I thought that after 10 minutes the UPS would shut itself down and wait until the power has been restored (that is what it is set to under on-battery shutdown behaviour) to turn itself back on. So what ended up happening is I pulled the plug, the servers shutdown in the right amount of time but the UPS just kept going and almost drained the battery after 35 minutes. I couldn’t actually stick around to see what would happen when the battery would be drained. Am I missing some configuration settings in order to get the desired effect to happen?

Thanks

[BillP · Accepted solution]

This reply was originally posted by Angela on APC forums on 2/8/2011

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what is your total runtime?

what the low battery signaling time means is that when X amount of runtime is remaining, in your case 5 minutes, then initiate a low battery message to all of your PCNS clients, then the UPS will still be running on battery for those 5 minutes, then it will have an additional delay of 5 minutes.

what you should do is on your PCNS clients, on the last server to shutdown ONLY, configure the PCNS software to turn the UPS off after the client shuts down. so, when everything is shutdown, it will send a message to the UPS to turn off. I believe this is under Configure Shutdown on the PCNS web interface configuration.

by default, if you just install PCNS and don't do any configuration, it will shutdown based on that low battery duration as a "fail safe" method of notifying devices attached to shutdown because the UPS is running low on battery power.

hope that helps.

[toolbox_apc]

This was originally posted on APC forums on 2/8/2011

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Thanks. That makes sense. I was misinterpreting the help file. Cheers.

[ACMIitsupport_apc]

This was originally posted on APC forums on 3/7/2011

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I am wondering if others find this explanation makes sense?

I understand that Low Battery Duration is calculated as an amount left to run. The suggestion is made to "configure the PCNS software to turn the UPS off after the client shuts down. so, when everything is shutdown, it will send a message to the UPS to turn off." The PCNS agent runs under the operating system of the host server. Even under VMware that is essentially true although in that case its the hypervisor. Either way once the host has shut down, there is no longer any PCNS agent to send a message. So how can the PCNS software turn off the UPS after the client (the host) has shut down? Its no longer operating. It can't do anything.

I think a more likely explanation is that PCNS sends a message to the UPS/NMC just before it triggers OS shutdown (after would be too risky) telling it to shut down the UPS after a defined time interval. From other reading that interval is Low Battery Duration + Shutdown Delay.

I still don't understand how a UPS which has said "I have enough battery to run for Low Battery Duration" can run for that long and still run on for Shutdown Delay too. Perhaps that is a subject for another thread.

Message was edited by: ACMIitsupport