Two servers, redundant power suplpies, and two UPS with NMC

[Anonymous user]

Hi there!

I have a configuration question. I'm not sure if I should be using Network Shutdown Utility or Sync Control, or both? I think I read you should not use both but the solution is not clear.

Here is a general scenario:

I have two Smart-UPS 1500 and each have an NMC with v3.61. Each UPS is on a differnet electrical circuit. One SU is named UPS "A" and the other is "B"

I have two HP servers each running Windows 2003 and each with redundant power supplies. I call them Server1 and Server2, and each has power supply1 and power supply2.

Power Supply1 from Server1 is connected to UPS "A"
Power Supply2 from Server1 is connected to UPS "B"
Power Supply1 from Server2 is connected to UPS "A"
Power Supply2 from Server2 is connected to UPS "B"

When battery expires on UPS "A", I do not want a shutdown control request sent to the servers unless UPS "B" battery runtime is very low. The reverse is also required: when UPS "B" battery runtime is very low, the servers should not recevie a shutdown control request unless battery "A" is also expired.

Please advise the best method to achieve thus.

Thank you!
-Bob

[BillP]

Hi Bob,

The synchronization option allows you to have two or more UPS units with their output synched up with one another. In this scenario, someone can remotely turn off or reboot one UPS and it will turn off/reboot other UPS units in the same sync group. This option is primarily used in cases where someone has either a server or switch that has redundant power supplies. You would need one UPS per power supply. If one UPS were to fail, then the other UPS will support the other power supply. However, if the you need to reboot the server you need to make sure that all power supplies are being rebooted. In this case, the sync group allows you to reboot one UPS, which in turn, reboots all that are part of the sync group. The problem that could occur is that if you had two UPS units that are part of the same sync group and are the two UPS' being monitored through PowerChute Network Shutdown (PCNS). If you were to turn off/reboot one of the UPS units, the other would turn off/reboot as well. When this happens, the server would turn off/reboot as well. This is why we don't advise enabling sync control when using PCNS.

For what you would like to do you will want to install PCNS on each computer setting it up for multiple UPS and putting in the IP of each Network Management Card NMC. In this setup when one UPS has to shutdown for some reason it will send a signal to the PCNS clients installed on each computer. The PCNS clients will wait until they have received a low battery signal (or whatever events you have configured to shutdown the servers) from both UPS before starting to shut them down. So even though it sends the signal to PCNS it takes an event from each UPS to trigger anything.

[Anonymous user]

Good morning Powerman,

Thanks for the easy to understand response.

Can you give me some info on how to test this scenario? I suppose the best way is to run the battery down on both UPS. But I'm wondering what happens under different scenario's. If UPS-A cannot be reach via network, is accidently unplugged or cut, or maybe the UPS just shutdown, what does PCNS do? does PCNS treat this state the same as if the battery had been discharged during a typical power outage on a single UPS?

I guess what I am looking for is an answer to the question, what are all the requirements which have to be met for the server to be shutdown. Has anyone done testing or a whitepaper on this?

Thanks a bunch!
-Bob

Message was edited by: littleroot

[BillP]

FYI, there are three events that PCNS will not wait for a signal from both UPSs/network management cards to force a shutdown. they are:

1. Lost Network Communication
2. Lost UPS Communication
3. Environmental Monitoring Card events

[taken from this article|http://nam-en.apc.com/cgi-bin/nam_en.cfg/php/enduser/std_adp.php?p_faqid=3143]

that may answer part of your question..

[Anonymous user]

Interesting. I'm not sure the article confirms what I experienced this morning in a test with all the "defaults" set on the NMC's and PCNS.

Test setup: One test server had PCNS connection with two SU UPS each with NMC's.

We disconnected AC power to both UPS and each had about %30 percent load so it took about 40 minutes to drain. UPS-A I really rather not reboot because we had a produciton workstation on it, so when the battery extremely low warning came I unplugged the network cable from the NMC and restored power to UPS-A. Then five minutes later when UPS-B got extrememly low battery warning the server was shutdown.

I like the resutls, but now I'm scratching my head wondering why the article said it would not do a shutdown if net cable was lost on either UPS. The test passed but now I'm trying to similarte what the article said.

I'm thinking a test where I start with everything the same as the test mentioned above, battery full everything normal, but before disconnecting power to UPS-A I am going to pull the netowrk cable out of UPS-B. When UPS-A battery is drained I hope the server will receive a shutdown command....

Thanks again guys. So far it is working, - I just cannot make it fail. 🙂

[BillP · Accepted solution]

it wont do a shutdown by default if communication is lost with the network management card, but if you configure that event to shut the particular PCNS client down, it will only wait until it receives that event from one of the NMCs rather than both.