Merge branch 'collectd-4.1' into collectd-4.2

[collectd.git] / src / collectd-snmp.pod

diff --git a/src/collectd-snmp.pod b/src/collectd-snmp.pod
index 00d41e5..ea49029 100644 (file)
--- a/src/collectd-snmp.pod
+++ b/src/collectd-snmp.pod
@@ -11,12 +11,14 @@ collectd-snmp - Documentation of collectd's C<snmp plugin>
       Type "voltage"
       Table false
       Instance "input_line1"
+      Scale 0.1
       Values "SNMPv2-SMI::enterprises.6050.5.4.1.1.2.1"
     </Data>
     <Data "hr_users">
       Type "users"
       Table false
       Instance ""
+      Shift -1
       Values "HOST-RESOURCES-MIB::hrSystemNumUsers.0"
     </Data>
     <Data "std_traffic">
@@ -128,14 +130,31 @@ Sets the type-instance of the values that are dispatched. The meaning of this
 setting depends on whether B<Table> is set to I<true> or I<false>:
 
 If B<Table> is set to I<true>, I<Instance> is interpreted as an SNMP-prefix
-that will return a list of strings. Those strings are then used as the actual
+that will return a list of values. Those values are then used as the actual
 type-instance. An example would be the C<IF-MIB::ifDescr> subtree.
 L<variables(5)> from the SNMP distribution describes the format of OIDs.
 
+If B<Table> is set to I<true> and B<Instance> is omitted, then "SUBID" will be
+used as the instance.
+
 If B<Table> is set to I<false> the actual string configured for I<Instance> is
 copied into the value-list. In this case I<Instance> may be empty, i.E<nbsp>e.
 "".
 
+=item B<InstancePrefix> I<String>
+
+If B<Table> is set to I<true>, you may feel the need to add something to the
+instance of the files. If set, I<String> is prepended to the instance as
+determined by querying the agent. When B<Table> is set to I<false> this option
+has no effect.
+
+The C<UPS-MIB> is an example where you need this setting: It has voltages of
+the inlets, outlets and the battery of an UPS. However, it doesn't provide a
+descriptive column for these voltages. In this case having 1, 2,E<nbsp>... as
+instances is not enough, because the inlet voltages and outlet voltages may
+both have the subids 1, 2,E<nbsp>... You can use this setting to distinguish
+between the different voltages.
+
 =item B<Values> I<OID> [I<OID> ...]
 
 Configures the values to be queried from the SNMP host. The meaning slightly
@@ -151,6 +170,24 @@ If B<Table> is set to I<false>, each I<OID> must be the OID of exactly one
 value, e.E<nbsp>g. C<IF-MIB::ifInOctets.3> for the third counter of incoming
 traffic.
 
+=item B<Scale> I<Value>
+
+The gauge-values returned by the SNMP-agent are multiplied by I<Value>.  This
+is useful when values are transfered as a fixed point real number. For example,
+thermometers may transfer B<243> but actually mean B<24.3>, so you can specify
+a scale value of B<0.1> to correct this. The default value is of course B<1.0>.
+
+This value is not applied to counter-values.
+
+=item B<Shift> I<Value>
+
+I<Value> is added to gauge-values returned by the SNMP-agent after they have
+been multiplied by any B<Scale> value. If, for example, a thermometer returns
+degrees Kelvin you could specify a shift of B<273.15> here to store values in
+degrees Celsius. The default value is is course B<0.0>.
+
+This value is not applied to counter-values.
+
 =back
 
 =head2 The Host block