Proxmox 3 node cluster with two apc ups

[bfoss]

i have three host each with two power supplies, each one is plug into two apc ups's. I know how to setup the APC's to talk to a host and shutdown workloads, my question is should i have each host talk to both ups's? And what happens if one ups loses power but the other one doesn't, is it smart enough to know it still has power from the other ups?

Or should i tell Host one talk to ups one and host two talk to ups two? so i one loses power it will shutdown and failover to the other host? Not sure then what to tell the third host to monitor for power? Any input would be helpful, i usually only have one APC.

 

[tomservo]

You need quorum for your cluster. Having only one host out of the 3 up will basically be the same as all 3 being down because it won't run any VMs because it can't get quorum. So having 2 monitoring one UPS and one monitoring the other isn't a great option.

It would make more sense to configure your UPS monitoring so that all 3 machines are watching both UPSs, and shutdown when both are at whatever critical level you want. When choosing the limits keep in mind that if one UPS dies, the entire load will be carried by the other. So if UPS1 has about 5 minutes left, and UPS2 stops supply power because its batteries are dead, then UPS1 actually has 2.5 minutes or less left, so set the critical limit higher than you would for more simple setups.

The NUT UPS monitor software makes this pretty easy. In the upsmon config you would have two "MONITOR" lines, one for each UPS. Then you would also have a "MINSUPPLIES 1" to say that this machine needs at least 1 UPS in good state, so when the last one goes to critical shutdown will start. You should really read the man pages and stuff for the details.