Number of threads to start for reading plugins. The default value is B<5>, but
you may want to increase this if you have more than five plugins that take a
-long time to read. Mostly those are plugin that do network-IO. Setting this to
-a value higher than the number of plugins you've loaded is totally useless.
+long time to read. Mostly those are plugins that do network-IO. Setting this to
+a value higher than the number of registered read callbacks is not recommended.
+
+=item B<WriteThreads> I<Num>
+
+Number of threads to start for dispatching value lists to write plugins. The
+default value is B<5>, but you may want to increase this if you have more than
+five plugins that may take relatively long to write to.
=item B<Hostname> I<Name>
blocks you want to refer to must be placed above the database block you want to
refer to them from.
+=item B<Host> I<Hostname>
+
+Sets the B<host> field of I<value lists> to I<Hostname> when dispatching
+values. Defaults to the global hostname setting.
+
=back
=head2 Plugin C<df>
=back
+=head2 Plugin C<write_riemann>
+
+The I<write_riemann plugin> will send values to I<Riemann>, a powerfull stream
+aggregation and monitoring system. The plugin sends I<Protobuf> encoded data to
+I<Riemann> using UDP packets.
+
+Synopsis:
+
+ <Plugin "write_riemann">
+ <Node "example">
+ Host "localhost"
+ Port "5555"
+ StoreRates false
+ Delay 10
+ </Node>
+ Tag "foobar"
+ </Plugin>
+
+The following options are understood by the I<write_riemann plugin>:
+
+=over 4
+
+=item E<lt>B<Node> I<Name>E<gt>
+
+The plugin's configuration consists of one or more B<Node> blocks. Each block
+is given a unique I<Name> and specifies one connection to an instance of
+I<Riemann>. Indise the B<Node> block, the following per-connection options are
+understood:
+
+=over 4
+
+=item B<Host> I<Address>
+
+Hostname or address to connect to. Defaults to C<localhost>.
+
+=item B<Port> I<Service>
+
+Service name or port number to connect to. Defaults to C<5555>.
+
+=item B<StoreRates> B<false>|B<true>
+
+If set to B<true> (the default), convert counter values to rates. If set to
+B<false> counter values are stored as is, i.e. as an increasing integer number.
+
+This will be reflected in the C<ds_type> tag: If B<StoreRates> is enabled,
+converted values will have "rate" appended to the data source type, e.g.
+C<ds_type:derive:rate>.
+
+=item B<AlwaysAppendDS> B<false>|B<true>
+
+If set the B<true>, append the name of the I<Data Source> (DS) to the
+"service", i.e. the field that, together with the "host" field, uniquely
+identifies a metric in I<Riemann>. If set to B<false> (the default), this is
+only done when there is more than one DS.
+
+=back
+
+=item B<Tag> I<String>
+
+Add the given string as an additional tag to the metric being sent to
+I<Riemann>.
+
+=back
+
=head1 THRESHOLD CONFIGURATION
Starting with version C<4.3.0> collectd has support for B<monitoring>. By that