-=head1 THRESHOLD CONFIGURATION
-
-Starting with version C<4.3.0> collectd has support for B<monitoring>. By that
-we mean that the values are not only stored or sent somewhere, but that they
-are judged and, if a problem is recognized, acted upon. The only action
-collectd takes itself is to generate and dispatch a "notification". Plugins can
-register to receive notifications and perform appropriate further actions.
-
-Since systems and what you expect them to do differ a lot, you can configure
-B<thresholds> for your values freely. This gives you a lot of flexibility but
-also a lot of responsibility.
-
-Every time a value is out of range a notification is dispatched. This means
-that the idle percentage of your CPU needs to be less then the configured
-threshold only once for a notification to be generated. There's no such thing
-as a moving average or similar - at least not now.
-
-Also, all values that match a threshold are considered to be relevant or
-"interesting". As a consequence collectd will issue a notification if they are
-not received for B<Timeout> iterations. The B<Timeout> configuration option is
-explained in section L<"GLOBAL OPTIONS">. If, for example, B<Timeout> is set to
-"2" (the default) and some hosts sends it's CPU statistics to the server every
-60 seconds, a notification will be dispatched after about 120 seconds. It may
-take a little longer because the timeout is checked only once each B<Interval>
-on the server.
-
-When a value comes within range again or is received after it was missing, an
-"OKAY-notification" is dispatched.
-
-Here is a configuration example to get you started. Read below for more
-information.
-
- <Threshold>
- <Type "foo">
- WarningMin 0.00
- WarningMax 1000.00
- FailureMin 0.00
- FailureMax 1200.00
- Invert false
- Instance "bar"
- </Type>
-
- <Plugin "interface">
- Instance "eth0"
- <Type "if_octets">
- FailureMax 10000000
- DataSource "rx"
- </Type>
- </Plugin>
-
- <Host "hostname">
- <Type "cpu">
- Instance "idle"
- FailureMin 10
- </Type>
-
- <Plugin "memory">
- <Type "memory">
- Instance "cached"
- WarningMin 100000000
- </Type>
- </Plugin>
-
- <Type "load">
- DataSource "midterm"
- FailureMax 4
- Hits 3
- Hysteresis 3
- </Type>
- </Host>
- </Threshold>
-
-There are basically two types of configuration statements: The C<Host>,
-C<Plugin>, and C<Type> blocks select the value for which a threshold should be
-configured. The C<Plugin> and C<Type> blocks may be specified further using the
-C<Instance> option. You can combine the block by nesting the blocks, though
-they must be nested in the above order, i.E<nbsp>e. C<Host> may contain either
-C<Plugin> and C<Type> blocks, C<Plugin> may only contain C<Type> blocks and
-C<Type> may not contain other blocks. If multiple blocks apply to the same
-value the most specific block is used.
-
-The other statements specify the threshold to configure. They B<must> be
-included in a C<Type> block. Currently the following statements are recognized:
-
-=over 4
-
-=item B<FailureMax> I<Value>
-
-=item B<WarningMax> I<Value>
-
-Sets the upper bound of acceptable values. If unset defaults to positive
-infinity. If a value is greater than B<FailureMax> a B<FAILURE> notification
-will be created. If the value is greater than B<WarningMax> but less than (or
-equal to) B<FailureMax> a B<WARNING> notification will be created.
-
-=item B<FailureMin> I<Value>
-
-=item B<WarningMin> I<Value>
-
-Sets the lower bound of acceptable values. If unset defaults to negative
-infinity. If a value is less than B<FailureMin> a B<FAILURE> notification will
-be created. If the value is less than B<WarningMin> but greater than (or equal
-to) B<FailureMin> a B<WARNING> notification will be created.
-
-=item B<DataSource> I<DSName>
-
-Some data sets have more than one "data source". Interesting examples are the
-C<if_octets> data set, which has received (C<rx>) and sent (C<tx>) bytes and
-the C<disk_ops> data set, which holds C<read> and C<write> operations. The
-system load data set, C<load>, even has three data sources: C<shortterm>,
-C<midterm>, and C<longterm>.
-
-Normally, all data sources are checked against a configured threshold. If this
-is undesirable, or if you want to specify different limits for each data
-source, you can use the B<DataSource> option to have a threshold apply only to
-one data source.
-
-=item B<Invert> B<true>|B<false>
-
-If set to B<true> the range of acceptable values is inverted, i.E<nbsp>e.
-values between B<FailureMin> and B<FailureMax> (B<WarningMin> and
-B<WarningMax>) are not okay. Defaults to B<false>.
-
-=item B<Persist> B<true>|B<false>
-
-Sets how often notifications are generated. If set to B<true> one notification
-will be generated for each value that is out of the acceptable range. If set to
-B<false> (the default) then a notification is only generated if a value is out
-of range but the previous value was okay.
-
-This applies to missing values, too: If set to B<true> a notification about a
-missing value is generated once every B<Interval> seconds. If set to B<false>
-only one such notification is generated until the value appears again.
-
-=item B<Percentage> B<true>|B<false>
-
-If set to B<true>, the minimum and maximum values given are interpreted as
-percentage value, relative to the other data sources. This is helpful for
-example for the "df" type, where you may want to issue a warning when less than
-5E<nbsp>% of the total space is available. Defaults to B<false>.
-
-=item B<Hits> I<Value>
-
-Sets the number of occurrences which the threshold must be arised before to
-dispatch any notification or, in other words, the number of B<Interval>s
-than the threshold must be match before dispatch any notification.
-
-=item B<Hysteresis> I<Value>
-
-Sets the hysteresis value for threshold. The hysteresis is a method to
-prevent flapping between states, until a new received value for
-a previously matched threshold down below the threshold condition
-(B<WarningMax>, B<FailureMin> or everthing else) minus the hysteresis value,
-the failure (respectively warning) state will be keep.
-
-=item B<Interesting> B<true>|B<false>
-
-If set to B<true> (the default), the threshold must be treated as
-interesting and, when a number of B<Timeout> values will lost, then
-a missing notification will be dispatched. On the other hand, if set to
-B<false>, the missing notification will never dispatched for this threshold.
-
-=back
-