Overview Of Network Ups Tools (Nut) - Tripp Lite B092-016 Owner's Manual

Chapter 8: Power and Environment
8.2.6

Overview of Network UPS Tools (NUT)

Network UPS Tools (NUT) is a group of open source programs that provide a common interface for monitoring and
administering UPS hardware; and ensuring safe shutdowns of the systems which are connected.
NUT can be configured using the Management Console as described above, or you can configure the tools and manage the
UPS's directly from the command line. This section provides an overview of NUT. You can find full documentation at http://www.
networkupstools.org/doc.
NUT is built on a networked model with a layered scheme of drivers, server and clients.
1. The driver programs talk directly to the UPS equipment and run on the same host as the NUT network server upsd. Drivers
are provided for a wide assortment of equipment from most of the popular UPS vendors and they understand the specific
language of each UPS and map it back to a compatibility layer. This means both an expensive "smart" protocol UPS and a
simple "power strip" model can be handled transparently.
2. The NUT network server program upsd is responsible for passing status data from the drivers to the client programs via
the network. upsd can cache the status from multiple UPS's and can then serve this status data to many clients. upsd
also contains access control features to limit the abilities of the clients (so only authorized hosts may monitor or control
the UPS hardware).
3. There are a number of NUT clients that connect to upsd to check on the status of the UPS hardware and do things based
on the status. These clients can run on the same host as the NUT server or they can communicate with the NUT server
over the network (enabling them to monitor any UPS anywhere).
The upsmon client enables servers that draw power through the UPS (i.e. Slaves of the UPS) to shutdown gracefully when
the battery power reaches critical. Additionally, one server is designated the Master of the UPS, and is responsible for
shutting down the UPS itself when all Slaves have shut down. Typically, the Master of the UPS is the one connected to the
UPS via serial or USB cable.
upsmon can monitor multiple UPS's, so high-end servers which receive power from multiple UPS's simultaneously won't
initiate a shutdown until the total power situation across all source UPS's becomes critical.
There also the two status/logging clients, upsc and upslog. The upsc client provides a quick way to poll the status of a
UPS. It can be used inside shell scripts and other programs that need UPS status information. upslog is a background
service that periodically polls the status of a UPS, writing it to a file.
All these clients run on the Console Server (for Management Console presentations) but they also are run remotely (on
locally powered servers and remote monitoring systems).
This layered NUT architecture enables:
• Multiple architecture support: NUT can manage serial and USB-connected models with the same common interface.
SNMP equipment can also be monitored (although at this stage this is still pre-release with experimental drivers and this
feature will be added to the embedded UPS tools in future release).
• Multiple clients monitoring one UPS: Multiple systems may monitor a single UPS using only their network connections.
There's a wide selection of client programs which support monitoring UPS hardware via NUT (Big Sister, Cacti, Nagios,
Windows and more). Refer to www.networkupstools.org/client-projects.)
So NUT supports the more complex power architectures found in data centers, computer rooms and NOCs where many UPS's
from many vendors power many systems with many clients and each of the larger UPS's power multiple devices and many of
these devices are themselves dual powered.
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