PCNS 2.2.4 Graceful Shutdown Process

[mcctech_apc]

This was originally posted on APC forums on 10/13/2010

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Hi all,

SMX1500RM2UNC (AP9631 w/ v5.1.3 firmware)
PCNS 2.2.4 (win7 64bit)

I am currently in the process of testing PCNS shutdown behaviors and would like to know what I should expect from this particular combo.

If I specify the 'on battery' event to trigger a shutdown after 5 minutes and the option to turn off the UPS after the client has shutdown is enabled, I want to know what to expect and the time frames involved after the client OS has gracefully shutdown assuming no external commands are executed and 'shutdown delay = 10secs'.

Should the UPS turn off after the 5 min shutdown + 10seconds or are there other built-in timers that I should know about?

My concern is that if the UPS shutdown procedure has started and then power is restored and somebody decides to manually turn on a machine, that the shutdown procedure will continue to execute, thus the UPS and groups are reset taking the machine down with it and corrupting drive(s).

I basically want connected machines to shutdown gracefully via PCNS but then power-on again after power is restored without any human intervention. My understanding is that the 'shutdown UPS after' option must be enabled for this to happen (obviously the last machine to shutdown).

TIA.

[BillP]

This reply was originally posted by Angela on APC forums on 10/13/2010

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check out the picture (from the PCNS help file) that is in [this knowledgebase article|http://nam-en.apc.com/app/answers/detail/a_id/10563] to help you understand what is expected.

that article doesnt have much to do with the question to asked but it has a good picture. alternatively, you can get the same image from the PCNS help file.

[mcctech_apc]

This was originally posted on APC forums on 10/13/2010

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Thanks. Yeah, I saw that in the PCNS help file last week, but I was in the process of working out some other issues with tech support - bad PSU in the workstation was the blame.

So if I understand correctly from #4, the UPS begins its shutdown process by waiting the low battery duration (in my case set to 5 mins). Then a built-in 2 min wait timer has to expire. The UPS reboot process starts, and waits the shutdown delay (in my case set to 10 secs).

So is it correct in assuming that I am looking at 5 mins + 2 mins + 10 sec = 7mins 10 secs minimum waiting time for the UPS to turn off AFTER the machine gracefully shuts down?

Can you explain what happens if power is restored after the UPS shutdown process has begun? From a quick test last week, it would appear as if the shutdown process continued after power was restored, thus making it dangerous to manually turn on the box.

From a logic point of view, I guess this is the only way to ensure that the box which was shutdown actually turns back on.

comments/thoughts?

[BillP]

This reply was originally posted by Angela on APC forums on 10/13/2010

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hi - you are incorrect.

the entire shutdown process including when the UPS is shutting down in addtion to the time the server has to shutdown is the entire 7 minutes and 10 seconds.

based on what you told us, you only configured the low battery duration in the NMC from the default 2 minutes to 5 minutes. after that, you should try that "force negotiation" setting mentioned in that article above. it will go out and make sure none of your PCNS clients have a command file with an additional delay time that it needs to account for. if it does, it will add that to the 5 minutes of time, which in your case, it doesnt appear to have done that. this also happens with the NMC is rebooted.

moving on, let's say you have an 60 minutes of runtime total. the input power is lost. the UPS will run on battery for ~55 minutes and then when there is 5 minutes remaining, the UPS will tell PCNS via the NMC that it has a low battery condition. the PCNS client will begin its OS shutdown and continue to shutdown while the UPS is in the low battery condition. then, it factors in an extra 2 minutes for unforseen circumstances and then it adds your shutdown delay of 10 seconds and then it goes ahead and turns the UPS off. if the power had come back during this 7 minutes and 10 seconds, the UPS will still shutdown since you cannot interrupt this process but it will reboot and turn back on and start providing output power (thus your PCNS client should see that power has returned and turn back on if the BIOS is set correctly).

if you try to turn on the PCNS client during the low battery condition, which will be 5 minutes of runtime remaining to when the UPS runs out of battery, yes it will force the PCNS client to shutdown again if you try to turn it back on. the NMC is unicasting the low battery signal and will force the PCNS client to shutdown so that it does not turn off ungracefully? (is that a word) and drop when the UPS cuts output power.

hope that helps!

[mcctech_apc · Accepted solution]

This was originally posted on APC forums on 10/13/2010

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Yes, explains things perfectly, thanks! I just confirmed the entire shutdown process and now I am trying to get command execution working, but I will start a new thread about this.