Graphing Metrics

Collecting performance data is only good if you can view the metrics that have been persisted. Meridian can display resource graphs that have been defined using RRDTool graphing syntax.

When using the MIB Compiler to generate collection definitions, the compiler will also create graph definitions for all the numeric values found in the MIB.

As an alternative to creating graphs within Meridian, you can also utilize our OpenNMS Plugin for Grafana to create dashboards displaying various resource graphs.

Graph definitions

Graphs are defined in in the ${OPENNMS_HOME}/etc/ directory via .properties file. These files are re-read whenever the "Resource Graphs" page is loaded in the Web UI and do not require restarting any daemons to apply changes. When the Resource Graphs page is loaded for a node, Meridian will look at the available metrics for the node, and will only display graphs where there are metrics for the columns defined in the graph. Within the configuration files, each graph is referred to as a "report".

While the graph directory name says snmp-graph, this system is used for displaying metrics regardless of which collector class was used.

The definition file should start with a reports property that is a comma-separated list of report names that are defined later on in the file. The list of report names should be followed by a group of definition properties.

Table 1. Graph definition properties
Property Description


The name of the graph. This is displayed next to the graph in the Web UI. The command parameter can also include a title attribute that will render a title within the graph itself.


Metric names to include in the graph. This is a comma-separated list of alias names from datacollection definitions.


The resource type that the column metrics belong to. This is often either nodeSnmp or interfaceSnmp, but may also be a custom resource type.


Parameters to feed into the graph rendering engine. This should be in RRDTool syntax.


This is an optional property that can be used to describe the graph, however it is not rendered within the Web UI.


This is an optional property that can be used to suppress other graphs from rendering. This would be used if you have similar graphs based on different metrics and only want to display one or the other, based on the available data.

Example report

Below is an example of a graph from the default file. The reports= setting at the top of the file should include a reference to mib2.HCbits. In/Out (High Speed) (1)
report.mib2.HCbits.suppress=mib2.bits (2)
report.mib2.HCbits.columns=ifHCInOctets,ifHCOutOctets (3)
report.mib2.HCbits.type=interfaceSnmp (4)
report.mib2.HCbits.command=--title="Bits In/Out (High Speed)" \ (5)
 --vertical-label="Bits per second" \
 DEF:octIn={rrd1}:ifHCInOctets:AVERAGE \
 DEF:octOut={rrd2}:ifHCOutOctets:AVERAGE \
 CDEF:rawbitsIn=octIn,8,* \
 CDEF:rawbitsOut=octOut,8,* \
 CDEF:rawbitsOutNeg=0,rawbitsOut,- \
 CDEF:bytesIn=octIn,UN,0,octIn,IF \
 CDEF:bytesOut=octOut,UN,0,octOut,IF \
 CDEF:outSum=bytesOut,{diffTime},* \
 CDEF:inSum=bytesIn,{diffTime},* \
 CDEF:totSum=outSum,inSum,+ \
 AREA:rawbitsIn#73d216 \
 LINE1:rawbitsIn#4e9a06:"In " \
 GPRINT:rawbitsIn:AVERAGE:"Avg  \\: %8.2lf %s" \
 GPRINT:rawbitsIn:MIN:"Min  \\: %8.2lf %s" \
 GPRINT:rawbitsIn:MAX:"Max  \\: %8.2lf %s\\n" \
 AREA:rawbitsOutNeg#729fcf \
 LINE1:rawbitsOutNeg#3465a4:"Out" \
 GPRINT:rawbitsOut:AVERAGE:"Avg  \\: %8.2lf %s" \
 GPRINT:rawbitsOut:MIN:"Min  \\: %8.2lf %s" \
 GPRINT:rawbitsOut:MAX:"Max  \\: %8.2lf %s\\n" \
 GPRINT:inSum:AVERAGE:"  Tot In  \\: %8.2lf %sBytes" \
 GPRINT:outSum:AVERAGE:" Tot Out  \\: %8.2lf %sBytes" \
 GPRINT:totSum:AVERAGE:" Tot  \\: %8.2lf %sBytes\\n"
1 The name of the graph to display.
2 Suppresses the mib2.bits graph from displaying if this graph can be rendered. This assumes there is another section that defines a graph with the property
3 List of metric alias names to include. These are referenced in the DEF commands based on the order they are listed. In this example, ifHCInOctets is {rrd1} and ifHCOutOctets is {rrd2}
4 The resource type of the graph. In this example, the columns defined should be collected as part of the SNMP Interface.
5 The RRDTool command to render the graph.