Network UPS Tools User Manual

Network UPS Tools User Manual 31 / 84
As an added bonus, this means you can move a running server from one UPS to another (for maintenance purpose for example)
without bringing it down since the minimum power will be provided at all times.
The MINSUPPLIES line tells upsmon that we need at least 2 power supplies to be receiving power from a good UPS (on line or
on battery, just not on battery and low battery).
Note
we could have used a Power Value of 1 for both UPS, and MINSUPPLIES set to 1 too. These values are purely arbitrary, so you
are free to use your own rules. Here, we have linked these values to the number of power supplies that each UPS is feeding
(2).
6.5.2 Multiple UPS shutdowns ordering
If you have multiple UPSes connected to your system, chances are that you need to shut them down in a specific order. The goal
is to shut down everything but the one keeping upsmon alive at first, then you do that one last.
To set the order in which your UPSes receive the shutdown commands, define the sdorder value in your ups.conf.
[bigone]
driver = usbhid-ups
port = auto
sdorder = 2
[littleguy]
driver = mge-shut
port = /dev/ttyS0
sdorder = 1
[misc]
driver = blazer_ser
port = /dev/ttyS1
sdorder = 0
The order runs from 0 to the highest number available. So, for this configuration, the order of shutdowns would be misc, littleguy,
and then bigone.
Note
If you have a UPS that shouldn’t be shutdown when running upsdrvctl shutdown, set the sdorder to -1.
6.5.3 Other redundancy configurations
There are a lot of ways to handle redundancy and they all come down to how many power supplies, power cords and independent
UPS connections you have. A system with a 1:1 cord:supply ratio has more wires stuffed behind it, but it’s much easier to move
things around since any given UPS drives a smaller percentage of the overall power.
More information can be found in the NUT user manual, and the various user manual pages.
7 Advanced usage and scheduling notes
upsmon can call out to a helper script or program when the device changes state. The example upsmon.conf has a full list of
which state changes are available - ONLINE, ONBATT, LOWBATT, and more.
There are two options, that will be presented in details:
• the simple approach: create your own helper, and manage all events and actions yourself,
• the advanced approach: use the NUT provided helper, called upssched.