PCNS and NMC configuration

[matoneo_apc]

This was originally posted on APC forums on 3/20/2015

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Hello, I appreciate some help since I cann't move on...

I have read a lot of documentation including great article from Steve Jenkins's blog (HowTo: Configure Low Battery Duration and PCNS to Shut Down with an APC SmartUPS) and I daresay I finaly understand most of terminology and logic.
My environment is two ESXi vMware hosts in a HA cluster including storage array and three additional physical servers are powered by two SMT2200RMI UPS's in redundant UPS configuration. PCNS for vMware is installed on one of the physical servers. Then I have one more SUA2200RMI UPS for additional two servers, switch and tape library in Single UPS configuration.While I am able to set configuration for single UPS scenario, I am a bit confused by my redundant "hybrid" one - if such configuration is even possible.
First I am confused by redundant UPS configuration. As I understood, first UPS is main and second acts as reserve. So does it mean that in case of power outage only one UPS will provide power supply for devices and only when it is (almost) out of juice, second ups will take over? How can I achieve this through the PCNS/NMC settings or is it automatic behaviour?
Second - Outlet group aware UPS - if I have vMware hosts and storage array plugged to outlet group, can I switch this group off from PSNS's server connected to Main group?
Third - can I use Low Battery condition (NMC's driven shutdown) to gracefully shutdown vMware stuff as well?

My aim is to hold everything online as long as possible.

Thank you in advance

[BillP]

This reply was originally posted by Bill on APC forums on 3/20/2015

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Marian,

I need to know what version of PCNS you have installed before I can make recommendation for the VMware configuration. If installing PCNS version 4.0 I suggest you review PCNS application note 180, PCNS VMware users guide and application note 98. In the users guide on page 64 there is a diagram that explains shut down process on systems with outlet groups.

As for the 2 servers attached to the SUA2200RMI you should install PCNS on each of the server and have them listen to the NMC in the SUA2200RMI for battery events. PCNS has the ability to run shut down scripts / command files so if you want you can write a script / command file that can be run to tell the switch and tape library to power down if they can accept remote shut down commands.

[matoneo_apc]

This was originally posted on APC forums on 3/25/2015

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Bill, thanks for reply and sorry for delay.
I have installed PCNS version 4.0.
First of all I would need to clarify what is the behavior of redundant ups configuration? If UPS1 shows in NMC's UI 38 min of Runtime Remaining and UPS2 show 33 min and I consider On battery shutdown delay, does it mean that I can count 38 + 33 of total remaining runtime i.e. in case of power outage first the UPS1 provides power for all devices and when its battery is exhausted only then UPS2 comes up ?

[BillP]

This reply was originally posted by Bill on APC forums on 3/25/2015

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Marian,

If 1 of the 2 UPS goes on battery then PCNS will record but not react to the event e.g. start OS shut down. If 1 UPS is on battery and then the second goes on battery PCNS will react if configured to do so. If both UPS go on battery then PCNS will react if configured to do so. Application note 98 discusses shut down scenarios for 2 UPS in a redundant configuration starting on page 4.

If both UPS are on battery and you have not configured any events shut down will begin when both UPS hits low battery or 1 is off and the other hits low battery. Normally if a computer has 2 power supplies it will split AC draw between them. If you have low battery at the NMC default of 2 minutes when the first UPS hit low battery at 31 minutes after power failure the OS will remain on however when the second hit low battery at 36 minutes after power failure the OS will be commended down. 

FYI: I don't recommend leaving the low battery setting at 2 minutes. It should be increased to allow for proper OS shut down and start up and an extra 2 to 4 minutes as a safety buffer. 

[matoneo_apc · Accepted solution]

This was originally posted on APC forums on 3/25/2015

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I see. I was confused by sentence "The first UPS provides all the power for the load, the additional UPS(s) act as reserve." on page 2 of Application note 98. So in case of "On battery event" configured shutdown, should be taken a higher of both Runtime Remaining values as decisive for shutdown delay assessment?

My low battery duration settings is actually 6 minutes.