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2 Unraid boxes, 1 UPS

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I just got a 36" deep 12U enclosure and have now installed both of my 4U Unraid boxes in it.  Due to the depths of both server chassis (SuperMicro 36-bay SC847 and Chenbro 48-bay RM43348), it would be really cramped having 2U UPS's to fitted in the enclosure along with a 1U network switch and a pair of 1U rack lights (one mounted in front and one at the rear of the rack). So I'm planning to install just one UPS, which would be one of the latest APC Smart-UPS X's with a Network Management Card.


I've come across both an Unraid thread here, as well as a StackExchange thread that discusses setting up apcupsd, so I delve into the apcupsd online manual link provided within Unraid's web interface and I need to do a master/slave configuration, but the setup instructions discuss the use of a configuration file.


Could this all be setup via Unraid's Settings->UPS Settings UPS Cable and UPS Type drop-down menus, and if so, what would be the appropriate selections on the "master" Unraid and "slave'' Unraid?


Or do I have to get down in the weeds by manually setting up a configuration file?

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  • Solution

Slave, note the IP address in the device field, set it to match the fixed IP of your master Unraid.


Master, nothing special, as long as the apcupsd is up and running it defaults to broadcasting as master on port 3551



Be sure the network path between the two boxes is powered during an outage, otherwise the slave box will never shut down. I recommend starting shutdown on the slave box almost immediately, so you can be sure it's down cleanly before the master box even starts to shut down. If you have VM's on the two boxes, install the apcupsd program on them as well, use the same slave settings, and start the shutdown first on them. Depending on load, capacity, and desired stress on batteries I recommend starting shutdown on VM's at the 60 second mark, the slave unraid box at 180 seconds, and the master at maximum 300 seconds. That way everything has time for a clean orderly shutdown without distressing the batteries by discharging below 50% or so. Once the heavy draws are shut down, you can leave the UPS running for a little while to keep the network alive.


Your situation may differ slightly, but the basic outline will probably be the same.

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12 hours ago, JonathanM said:


I find it mildly amusing that the UPS cable setting for slave is "ether", and the UPS type is "net"

ethernet, get it?


Yeah, yeah, small things for small minds.


I probably would never have figured out these settings ("ether" and "net") unless I block out some time to do trial and error with every single combination (which I would not have the patience for). MAYBE if I saw these two words in adjacent drop downs, I might have went straight to that combo; but split across two different web pages, nah, I'm a little too dense to pick up on that when I'm in hurry!

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