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APC UPS - Best Practice - configuring events and shutdown

Posted on 2011-09-11
Last Modified: 2013-12-11
Dear Experts;

Im really new in this field (UPS APC); so really need your help in configuring PCNS and UPS.

I have the servers with 2 psu (redundant); both attached to the UPS.
Is this the best practice? or should we have 1 attached to the wall and the other attached to the UPS? Please advise.

Our UPS is Smart UPS RT5000 RM
I installed the PCNS to all servers; but not really sure what is the best practice for configuring events and shutdown.

Which one  that needs to be configured to shutdown the system?


What is the best practice for this?

Please advise
Question by:DAHITSydney
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LVL 93

Expert Comment

by:John Hurst
ID: 36520600
The point of having 2 power supplies in a server is to imagine that one will fail and the other will keep going. Accordningly, you want both power supplies connected to UPS units.

Why? The very instant the power goes out, the power supply on the UPS will fail and the power supply connected to the wall will be OK (but the power is out). Murphy's Law is incredibily real.

One the second question, a medium to small UPS will want to shut down the computers after about 6 minutes in a power outage to provide time for an orderly shutdown ( which itself may take several minutes). You need to look at the UPS specifications and the default parameters it has. If you wish to change them, you should test with a simulated outage. Power outage is the main parameter to consider.

... Thinkpads_User
LVL 12

Expert Comment

ID: 36520733
I concur.. each power supply in the servers should be connected to a different power source. What we do is have multiple UPS devices on different electrical Circuits, then have each power supply in the servers connected to the different UPS'. the problem you have at the moment is if you connect 1 to the UPS and 1 to the wall, is what happens if there is a surge or a stop start event that causes the power supply to blow up ? is it going to take the servers motherboard / hard discs etc with it.. you can guarantee it wont.. you 'really' need another UPS for this to be fully redundant..

Author Comment

ID: 36520746
Hi experts;

thanks for the quick reply; very interesting point by psychofelix.

We do have 2 UPS; however they are different model; is this still work?
Also we have 1 power goes to UPS 1 and the other goes to UPS 2; does it mean we have the same clients for both UPS on the PCNS management card where we define the IP addresses for all clients?

also if one of the UPS is failing; the server will still run from the different power source; will the management card still sending the "shutdown" command to the server?

sorry; a lot of questions here; still very new with UPS world

please advise
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Author Comment

ID: 36520747
sorry: i meant
"IF we have 1 power goes to UPS 1 and the other goes to UPS 2; does it mean we have the same clients for both UPS on the PCNS management card where we define the IP addresses for all clients?"
LVL 12

Expert Comment

ID: 36520814
the 'clients' I assume you mean the APC software ? you'd set the two management agents with different IP addresses otherwise you wont be able to access them..

In terms of which one to send the shut down commands, personally I'd only configure the UPS with the largest capacity to issue any commands, that way you're ensured that you'll get the longest run time and the power 'may' come back on before it has to shut it down anyway..

dont have anything setup on the smaller UPS.. use it just as power conditioner and limited backup in case the primary power supply dies etc..

Author Comment

ID: 36520959
hi there,

how do you setup 2 management agents in 1 server? is there an option to setup 2 management IP address? I can't find it anywhere to setup 2 management IP addresses under PCNS. can you please help?

what happen if the primary ups goes down? is that mean the server won't have a graceful shutdown?

please advise
LVL 12

Accepted Solution

Steve earned 500 total points
ID: 36520978
thing is.. if the primary UPS goes down, you are still running on the secondary UPS.. if your primary goes down and your secondary is up, it wont be because aof a power failure because your primary UPS has more capasity than the secondary.. so it'd be due to a hardware failure of some sort.. if you setup the system health monitoring tools to email you on events then you'll know about the problem anyway and you can shut the server and get the issue fixed.

In terms of accessing both UPS' from one server, if they are IP based, just browse to them by IP address..


Author Comment

ID: 36533742
hi there,

just want to confirmed that we don't really have to do anything on the lower power PSU (ie: defining the IP addresses of clients in the management IP of UPS), etc; just simply plug the 2nd PSU from the server directly to the UPS?


Author Closing Comment

ID: 36714098
thanks very much for your help

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