X-Git-Url: https://git.octo.it/?a=blobdiff_plain;f=src%2Fcollectd.conf.pod;h=98b492d14f839868183787609cf43f743dd0a230;hb=b21ab82a9ffe2a74a29c1dd606cb2ca7db6cd985;hp=2be3c939fa410900bb27b30ec7b6a0c4ad12c22a;hpb=3b473acc5d4d27e5cf5101a4b8cc8a21c2bb7262;p=collectd.git

diff --git a/src/collectd.conf.pod b/src/collectd.conf.pod
index 2be3c939..98b492d1 100644
--- a/src/collectd.conf.pod
+++ b/src/collectd.conf.pod
@@ -1,3 +1,5 @@
+=encoding UTF-8
+
 =head1 NAME
 
 collectd.conf - Configuration for the system statistics collection daemon B<collectd>
@@ -7,11 +9,15 @@ collectd.conf - Configuration for the system statistics collection daemon B<coll
   BaseDir "/path/to/data/"
   PIDFile "/path/to/pidfile/collectd.pid"
   Server  "123.123.123.123" 12345
-
+  
   LoadPlugin cpu
   LoadPlugin load
+  
+  <LoadPlugin df>
+    Interval 3600
+  </LoadPlugin>
+  
   LoadPlugin ping
-
   <Plugin ping>
     Host "example.org"
     Host "provider.net"
@@ -25,22 +31,32 @@ controls which plugins to load. These plugins ultimately define collectd's
 behavior.
 
 The syntax of this config file is similar to the config file of the famous
-B<Apache Webserver>. Each line contains either a key-value-pair or a
-section-start or -end. Empty lines and everything after the hash-symbol `#' is
-ignored. Values are either string, enclosed in double-quotes,
-(floating-point-)numbers or a boolean expression, i.E<nbsp>e. either B<true> or
-B<false>. String containing of only alphanumeric characters and underscores do
-not need to be quoted. Lines may be wrapped by using `\' as the last character
-before the newline. This allows long lines to be split into multiple lines.
-Quoted strings may be wrapped as well. However, those are treated special in
-that whitespace at the beginning of the following lines will be ignored, which
-allows for nicely indenting the wrapped lines.
-
-The configuration is read and processed in order, i.E<nbsp>e. from top to
-bottom. So the plugins are loaded in the order listed in this config file. It
-is a good idea to load any logging plugins first in order to catch messages
-from plugins during configuration. Also, the C<LoadPlugin> option B<must> occur
-B<before> the C<E<lt>Plugin ...E<gt>> block.
+I<Apache> webserver. Each line contains either an option (a key and a list of
+one or more values) or a section-start or -end. Empty lines and everything
+after a non-quoted hash-symbol (C<#>) is ignored. I<Keys> are unquoted
+strings, consisting only of alphanumeric characters and the underscore (C<_>)
+character. Keys are handled case insensitive by I<collectd> itself and all
+plugins included with it. I<Values> can either be an I<unquoted string>, a
+I<quoted string> (enclosed in double-quotes) a I<number> or a I<boolean>
+expression. I<Unquoted strings> consist of only alphanumeric characters and
+underscores (C<_>) and do not need to be quoted. I<Quoted strings> are
+enclosed in double quotes (C<">). You can use the backslash character (C<\>)
+to include double quotes as part of the string. I<Numbers> can be specified in
+decimal and floating point format (using a dot C<.> as decimal separator),
+hexadecimal when using the C<0x> prefix and octal with a leading zero (C<0>).
+I<Boolean> values are either B<true> or B<false>.
+
+Lines may be wrapped by using C<\> as the last character before the newline.
+This allows long lines to be split into multiple lines. Quoted strings may be
+wrapped as well. However, those are treated special in that whitespace at the
+beginning of the following lines will be ignored, which allows for nicely
+indenting the wrapped lines.
+
+The configuration is read and processed in order, i.e. from top to bottom. So
+the plugins are loaded in the order listed in this config file. It is a good
+idea to load any logging plugins first in order to catch messages from plugins
+during configuration. Also, the C<LoadPlugin> option B<must> occur B<before>
+the appropriate C<E<lt>Plugin ...E<gt>> block.
 
 =head1 GLOBAL OPTIONS
 
@@ -63,6 +79,7 @@ options are allowed inside a B<LoadPlugin> block:
 
   <LoadPlugin perl>
     Globals true
+    Interval 10
   </LoadPlugin>
 
 =over 4
@@ -86,6 +103,12 @@ By default, this is disabled. As a special exception, if the plugin name is
 either C<perl> or C<python>, the default is changed to enabled in order to keep
 the average user from ever having to deal with this low level linking stuff.
 
+=item B<Interval> I<Seconds>
+
+Sets a plugin-specific interval for collecting metrics. This overrides the
+global B<Interval> setting. If a plugin provides own support for specifying an
+interval, that setting will take precedence.
+
 =back
 
 =item B<Include> I<Path>
@@ -98,6 +121,29 @@ use statements like the following:
 
   Include "/etc/collectd.d/*.conf"
 
+Starting with version 5.3, this may also be a block in which further options
+affecting the behavior of B<Include> may be specified. The following option is
+currently allowed:
+
+  <Include "/etc/collectd.d">
+    Filter "*.conf"
+  </Include>
+
+=over 4
+
+=item B<Filter> I<pattern>
+
+If the C<fnmatch> function is available on your system, a shell-like wildcard
+I<pattern> may be specified to filter which files to include. This may be used
+in combination with recursively including a directory to easily be able to
+arbitrarily mix configuration files and other documents (e.g. README files).
+The given example is similar to the first example above but includes all files
+matching C<*.conf> in any subdirectory of C</etc/collectd.d>:
+
+  Include "/etc/collectd.d" "*.conf"
+
+=back
+
 If more than one files are included by a single B<Include> option, the files
 will be included in lexicographical order (as defined by the C<strcmp>
 function). Thus, you can e.E<nbsp>g. use numbered prefixes to specify the
@@ -151,8 +197,14 @@ see L<collectd-threshold(5)> for details.
 
 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>
 
@@ -183,12 +235,183 @@ C<Plugin>-Section. Which options exist depends on the plugin used. Some plugins
 require external configuration, too. The C<apache plugin>, for example,
 required C<mod_status> to be configured in the webserver you're going to
 collect data from. These plugins are listed below as well, even if they don't
-require any configuration within collectd's configfile.
+require any configuration within collectd's configuration file.
 
 A list of all plugins and a short summary for each plugin can be found in the
 F<README> file shipped with the sourcecode and hopefully binary packets as
 well.
 
+=head2 Plugin C<aggregation>
+
+The I<Aggregation plugin> makes it possible to aggregate several values into
+one using aggregation functions such as I<sum>, I<average>, I<min> and I<max>.
+This can be put to a wide variety of uses, e.g. average and total CPU
+statistics for your entire fleet.
+
+The grouping is powerful but, as with many powerful tools, may be a bit
+difficult to wrap your head around. The grouping will therefore be
+demonstrated using an example: The average and sum of the CPU usage across
+all CPUs of each host is to be calculated.
+
+To select all the affected values for our example, set C<Plugin cpu> and
+C<Type cpu>. The other values are left unspecified, meaning "all values". The
+I<Host>, I<Plugin>, I<PluginInstance>, I<Type> and I<TypeInstance> options
+work as if they were specified in the C<WHERE> clause of an C<SELECT> SQL
+statement.
+
+  Plugin "cpu"
+  Type "cpu"
+
+Although the I<Host>, I<PluginInstance> (CPU number, i.e. 0, 1, 2, ...)  and
+I<TypeInstance> (idle, user, system, ...) fields are left unspecified in the
+example, the intention is to have a new value for each host / type instance
+pair. This is achieved by "grouping" the values using the C<GroupBy> option.
+It can be specified multiple times to group by more than one field.
+
+  GroupBy "Host"
+  GroupBy "TypeInstance"
+
+We do neither specify nor group by I<plugin instance> (the CPU number), so all
+metrics that differ in the CPU number only will be aggregated. Each
+aggregation needs I<at least one> such field, otherwise no aggregation would
+take place.
+
+The full example configuration looks like this:
+
+ <Plugin "aggregation">
+   <Aggregation>
+     Plugin "cpu"
+     Type "cpu"
+     
+     GroupBy "Host"
+     GroupBy "TypeInstance"
+     
+     CalculateSum true
+     CalculateAverage true
+   </Aggregation>
+ </Plugin>
+
+There are a couple of limitations you should be aware of:
+
+=over 4
+
+=item
+
+The I<Type> cannot be left unspecified, because it is not reasonable to add
+apples to oranges. Also, the internal lookup structure won't work if you try
+to group by type.
+
+=item
+
+There must be at least one unspecified, ungrouped field. Otherwise nothing
+will be aggregated.
+
+=back
+
+As you can see in the example above, each aggregation has its own
+B<Aggregation> block. You can have multiple aggregation blocks and aggregation
+blocks may match the same values, i.e. one value list can update multiple
+aggregations. The following options are valid inside B<Aggregation> blocks:
+
+=over 4
+
+=item B<Host> I<Host>
+
+=item B<Plugin> I<Plugin>
+
+=item B<PluginInstance> I<PluginInstance>
+
+=item B<Type> I<Type>
+
+=item B<TypeInstance> I<TypeInstance>
+
+Selects the value lists to be added to this aggregation. B<Type> must be a
+valid data set name, see L<types.db(5)> for details.
+
+If the string starts with and ends with a slash (C</>), the string is
+interpreted as a I<regular expression>. The regex flavor used are POSIX
+extended regular expressions as described in L<regex(7)>. Example usage:
+
+ Host "/^db[0-9]\\.example\\.com$/"
+
+=item B<GroupBy> B<Host>|B<Plugin>|B<PluginInstance>|B<TypeInstance>
+
+Group valued by the specified field. The B<GroupBy> option may be repeated to
+group by multiple fields.
+
+=item B<SetHost> I<Host>
+
+=item B<SetPlugin> I<Plugin>
+
+=item B<SetPluginInstance> I<PluginInstance>
+
+=item B<SetTypeInstance> I<TypeInstance>
+
+Sets the appropriate part of the identifier to the provided string.
+
+The I<PluginInstance> should include the placeholder C<%{aggregation}> which
+will be replaced with the aggregation function, e.g. "average". Not including
+the placeholder will result in duplication warnings and/or messed up values if
+more than one aggregation function are enabled.
+
+The following example calculates the average usage of all "even" CPUs:
+
+ <Plugin "aggregation">
+   <Aggregation>
+     Plugin "cpu"
+     PluginInstance "/[0,2,4,6,8]$/"
+     Type "cpu"
+     
+     SetPlugin "cpu"
+     SetPluginInstance "even-%{aggregation}"
+     
+     GroupBy "Host"
+     GroupBy "TypeInstance"
+     
+     CalculateAverage true
+   </Aggregation>
+ </Plugin>
+
+This will create the files:
+
+=over 4
+
+=item
+
+foo.example.com/cpu-even-average/cpu-idle
+
+=item
+
+foo.example.com/cpu-even-average/cpu-system
+
+=item
+
+foo.example.com/cpu-even-average/cpu-user
+
+=item
+
+...
+
+=back
+
+=item B<CalculateNum> B<true>|B<false>
+
+=item B<CalculateSum> B<true>|B<false>
+
+=item B<CalculateAverage> B<true>|B<false>
+
+=item B<CalculateMinimum> B<true>|B<false>
+
+=item B<CalculateMaximum> B<true>|B<false>
+
+=item B<CalculateStddev> B<true>|B<false>
+
+Boolean options for enabling calculation of the number of value lists, their
+sum, average, minimum, maximum andE<nbsp>/ or standard deviation. All options
+are disabled by default.
+
+=back
+
 =head2 Plugin C<amqp>
 
 The I<AMQMP plugin> can be used to communicate with other instances of
@@ -210,6 +433,8 @@ possibly filtering or messages.
  #   Persistent false
  #   Format "command"
  #   StoreRates false
+ #   GraphitePrefix "collectd."
+ #   GraphiteEscapeChar "_"
    </Publish>
    
    # Receive values from an AMQP broker
@@ -299,7 +524,7 @@ mode will be used, i.e. delivery is guaranteed. If set to B<false> (the
 default), the I<transient> delivery mode will be used, i.e. messages may be
 lost due to high load, overflowing queues or similar issues.
 
-=item B<Format> B<Command>|B<JSON> (Publish only)
+=item B<Format> B<Command>|B<JSON>|B<Graphite> (Publish only)
 
 Selects the format in which messages are sent to the broker. If set to
 B<Command> (the default), values are sent as C<PUTVAL> commands which are
@@ -310,6 +535,10 @@ If set to B<JSON>, the values are encoded in the I<JavaScript Object Notation>,
 an easy and straight forward exchange format. The C<Content-Type> header field
 will be set to C<application/json>.
 
+If set to B<Graphite>, values are encoded in the I<Graphite> format, which is
+"<metric> <value> <timestamp>\n". The C<Content-Type> header field will be set to
+C<text/graphite>.
+
 A subscribing client I<should> use the C<Content-Type> header field to
 determine how to decode the values. Currently, the I<AMQP plugin> itself can
 only decode the B<Command> format.
@@ -324,6 +553,25 @@ using the internal value cache.
 Please note that currently this option is only used if the B<Format> option has
 been set to B<JSON>.
 
+=item B<GraphitePrefix> (Publish and B<Format>=I<Graphite> only)
+
+A prefix can be added in the metric name when outputting in the I<Graphite> format.
+It's added before the I<Host> name.
+Metric name will be "<prefix><host><postfix><plugin><type><name>"
+
+=item B<GraphitePostfix> (Publish and B<Format>=I<Graphite> only)
+
+A postfix can be added in the metric name when outputting in the I<Graphite> format.
+It's added after the I<Host> name.
+Metric name will be "<prefix><host><postfix><plugin><type><name>"
+
+=item B<GraphiteEscapeChar> (Publish and B<Format>=I<Graphite> only)
+
+Specify a character to replace dots (.) in the host part of the metric name.
+In I<Graphite> metric name, dots are used as separators between different
+metric parts (host, plugin, type).
+Default is "_" (I<Underscore>).
+
 =back
 
 =head2 Plugin C<apache>
@@ -415,6 +663,12 @@ B<apcupsd> can handle it.
 
 TCP-Port to connect to. Defaults to B<3551>.
 
+=item B<ReportSeconds> B<true|false>
+
+If set to B<true>, the time reported in the C<timeleft> metric will be
+converted to seconds. This is the recommended setting. If set to B<false>, the
+default for backwards compatibility, the time will be reported in minutes.
+
 =back
 
 =head2 Plugin C<ascent>
@@ -706,6 +960,19 @@ File that holds one or more SSL certificates. If you want to use HTTPS you will
 possibly need this option. What CA certificates come bundled with C<libcurl>
 and are checked by default depends on the distribution you use.
 
+=item B<Header> I<Header>
+
+A HTTP header to add to the request. Multiple headers are added if this option
+is specified more than once.
+
+=item B<Post> I<Body>
+
+Specifies that the HTTP operation should be a POST instead of a GET. The
+complete data to be posted is given as the argument.  This option will usually
+need to be accompanied by a B<Header> option to set an appropriate
+C<Content-Type> for the post body (e.g. to
+C<application/x-www-form-urlencoded>).
+
 =item B<MeasureResponseTime> B<true>|B<false>
 
 Measure response time for the request. If this setting is enabled, B<Match>
@@ -764,31 +1031,15 @@ The following options are valid within B<URL> blocks:
 Sets the plugin instance to I<Instance>.
 
 =item B<User> I<Name>
-
-Username to use if authorization is required to read the page.
-
 =item B<Password> I<Password>
-
-Password to use if authorization is required to read the page.
-
 =item B<VerifyPeer> B<true>|B<false>
-
-Enable or disable peer SSL certificate verification. See
-L<http://curl.haxx.se/docs/sslcerts.html> for details. Enabled by default.
-
 =item B<VerifyHost> B<true>|B<false>
-
-Enable or disable peer host name verification. If enabled, the plugin checks if
-the C<Common Name> or a C<Subject Alternate Name> field of the SSL certificate
-matches the host name provided by the B<URL> option. If this identity check
-fails, the connection is aborted. Obviously, only works when connecting to a
-SSL enabled server. Enabled by default.
-
 =item B<CACert> I<file>
+=item B<Header> I<Header>
+=item B<Post> I<Body>
 
-File that holds one or more SSL certificates. If you want to use HTTPS you will
-possibly need this option. What CA certificates come bundled with C<libcurl>
-and are checked by default depends on the distribution you use.
+These options behave exactly equivalent to the appropriate options of the
+I<cURL> plugin. Please see there for a detailed description.
 
 =back
 
@@ -857,14 +1108,34 @@ host name setting.
 Use I<Instance> as the plugin instance when submitting values. Defaults to an
 empty string (no plugin instance).
 
+=item B<Namespace> I<Prefix> I<URL>
+
+If an XPath expression references namespaces, they must be specified
+with this option. I<Prefix> is the "namespace prefix" used in the XML document.
+I<URL> is the "namespace name", an URI reference uniquely identifying the
+namespace. The option can be repeated to register multiple namespaces.
+
+Examples:
+
+  Namespace "s" "http://schemas.xmlsoap.org/soap/envelope/"
+  Namespace "m" "http://www.w3.org/1998/Math/MathML"
+
 =item B<User> I<User>
+
 =item B<Password> I<Password>
+
 =item B<VerifyPeer> B<true>|B<false>
+
 =item B<VerifyHost> B<true>|B<false>
+
 =item B<CACert> I<CA Cert File>
 
+=item B<Header> I<Header>
+
+=item B<Post> I<Body>
+
 These options behave exactly equivalent to the appropriate options of the
-I<cURL> and I<cURL-JSON> plugins. Please see there for a detailed description.
+I<cURL plugin>. Please see there for a detailed description.
 
 =item E<lt>B<XPath> I<XPath-expression>E<gt>
 
@@ -1128,11 +1399,23 @@ documentation for each driver, somewhere at
 L<http://libdbi-drivers.sourceforge.net/>. However, the options "host",
 "username", "password", and "dbname" seem to be deE<nbsp>facto standards.
 
+DBDs can register two types of options: String options and numeric options. The
+plugin will use the C<dbi_conn_set_option> function when the configuration
+provides a string and the C<dbi_conn_require_option_numeric> function when the
+configuration provides a number. So these two lines will actually result in
+different calls being used:
+
+  DriverOption "Port" 1234      # numeric
+  DriverOption "Port" "1234"    # string
+
 Unfortunately, drivers are not too keen to report errors when an unknown option
 is passed to them, so invalid settings here may go unnoticed. This is not the
 plugin's fault, it will report errors if it gets them from the libraryE<nbsp>/
 the driver. If a driver complains about an option, the plugin will dump a
-complete list of all options understood by that driver to the log.
+complete list of all options understood by that driver to the log. There is no
+way to programatically find out if an option expects a string or a numeric
+argument, so you will have to refer to the appropriate DBD's documentation to
+find this out. Sorry.
 
 =item B<SelectDB> I<Database>
 
@@ -1147,6 +1430,11 @@ query needs to be defined I<before> this statement, i.E<nbsp>e. all query
 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>
@@ -1272,6 +1560,41 @@ at most B<16384> to prevent typos and dumb mistakes.
 
 =back
 
+=head2 Plugin C<ethstat>
+
+The I<ethstat plugin> collects information about network interface cards (NICs)
+by talking directly with the underlying kernel driver using L<ioctl(2)>.
+
+B<Synopsis:>
+
+ <Plugin "ethstat">
+   Interface "eth0"
+   Map "rx_csum_offload_errors" "if_rx_errors" "checksum_offload"
+   Map "multicast" "if_multicast"
+ </Plugin>
+
+B<Options:>
+
+=over 4
+
+=item B<Interface> I<Name>
+
+Collect statistical information about interface I<Name>.
+
+=item B<Map> I<Name> I<Type> [I<TypeInstance>]
+
+By default, the plugin will submit values as type C<derive> and I<type
+instance> set to I<Name>, the name of the metric as reported by the driver. If
+an appropriate B<Map> option exists, the given I<Type> and, optionally,
+I<TypeInstance> will be used.
+
+=item B<MappedOnly> B<true>|B<false>
+
+When set to B<true>, only metrics that can be mapped to to a I<type> will be
+collected, all other metrics will be ignored. Defaults to B<false>.
+
+=back
+
 =head2 Plugin C<exec>
 
 Please make sure to read L<collectd-exec(5)> before using this plugin. It
@@ -1822,6 +2145,31 @@ TCP-Port to connect to. Defaults to B<411>.
 
 =back
 
+=head2 Plugin C<md>
+
+The C<md plugin> collects information from Linux Software-RAID devices (md).
+
+All reported values are of the type C<md_disks>. Reported type instances are
+I<active>, I<failed> (present but not operational), I<spare> (hot stand-by) and
+I<missing> (physically absent) disks.
+
+=over 4
+
+=item B<Device> I<Device>
+
+Select md devices based on device name. The I<device name> is the basename of
+the device, i.e. the name of the block device without the leading C</dev/>.
+See B<IgnoreSelected> for more details.
+
+=item B<IgnoreSelected> B<true>|B<false>
+
+Invert device selection: If set to B<true>, all md devices B<except> those
+listed using B<Device> are collected. If B<false> (the default), only those
+listed are collected. If no configuration is given, the B<md> plugin will
+collect data from all md devices.
+
+=back
+
 =head2 Plugin C<memcachec>
 
 The C<memcachec plugin> connects to a memcached server, queries one or more
@@ -1879,6 +2227,17 @@ The C<memcached plugin> connects to a memcached server and queries statistics
 about cache utilization, memory and bandwidth used.
 L<http://www.danga.com/memcached/>
 
+ <Plugin "memcached">
+   <Instance "name">
+     Host "memcache.example.com"
+     Port 11211
+   </Instance>
+ </Plugin>
+
+The plugin configuration consists of one or more B<Instance> blocks which
+specify one I<memcached> connection each. Within the B<Instance> blocks, the
+following options are allowed:
+
 =over 4
 
 =item B<Host> I<Hostname>
@@ -1889,6 +2248,11 @@ Hostname to connect to. Defaults to B<127.0.0.1>.
 
 TCP-Port to connect to. Defaults to B<11211>.
 
+=item B<Socket> I<Path>
+
+Connect to I<memcached> using the UNIX domain socket at I<Path>. If this
+setting is given, the B<Host> and B<Port> settings are ignored.
+
 =back
 
 =head2 Plugin C<modbus>
@@ -2185,6 +2549,14 @@ Required capabilities are documented below.
       IgnoreSelectedSnapshot false
     </VolumeUsage>
     
+    <Quota>
+      Interval 60
+    </Quota>
+    
+    <Snapvault>
+      Interval 30
+    </Snapvault>
+    
     <System>
       Interval 30
       GetCPULoad     true
@@ -2192,6 +2564,13 @@ Required capabilities are documented below.
       GetDiskOps     true
       GetDiskIO      true
     </System>
+
+    <VFiler vfilerA>
+      Interval 60
+
+      SnapVault true
+      # ...
+    </VFiler>
    </Host>
  </Plugin>
 
@@ -2202,7 +2581,27 @@ The netapp plugin accepts the following configuration options:
 =item B<Host> I<Name>
 
 A host block defines one NetApp filer. It will appear in collectd with the name
-you specify here which does not have to be its real name nor its hostname.
+you specify here which does not have to be its real name nor its hostname (see
+the B<Address> option below).
+
+=item B<VFiler> I<Name>
+
+A B<VFiler> block may only be used inside a host block. It accepts all the
+same options as the B<Host> block (except for cascaded B<VFiler> blocks) and
+will execute all NetApp API commands in the context of the specified
+VFiler(R). It will appear in collectd with the name you specify here which
+does not have to be its real name. The VFiler name may be specified using the
+B<VFilerName> option. If this is not specified, it will default to the name
+you specify here.
+
+The VFiler block inherits all connection related settings from the surrounding
+B<Host> block (which appear before the B<VFiler> block) but they may be
+overwritten inside the B<VFiler> block.
+
+This feature is useful, for example, when using a VFiler as SnapVault target
+(supported since OnTap 8.1). In that case, the SnapVault statistics are not
+available in the host filer (vfiler0) but only in the respective VFiler
+context.
 
 =item B<Protocol> B<httpd>|B<http>
 
@@ -2246,6 +2645,19 @@ Mandatory
 
 Type: string
 
+=item B<VFilerName> I<Name>
+
+The name of the VFiler in which context to execute API commands. If not
+specified, the name provided to the B<VFiler> block will be used instead.
+
+Optional
+
+Type: string
+
+Default: name of the B<VFiler> block
+
+B<Note:> This option may only be used inside B<VFiler> blocks.
+
 =item B<Interval> I<Interval>
 
 B<TODO>
@@ -2576,6 +2988,38 @@ capacities will be selected anyway.
 
 =back
 
+=head3 The Quota block
+
+This will collect (tree) quota statistics (used disk space and number of used
+files). This mechanism is useful to get usage information for single qtrees.
+In case the quotas are not used for any other purpose, an entry similar to the
+following in C</etc/quotas> would be sufficient:
+
+  /vol/volA/some_qtree tree - - - - -
+
+After adding the entry, issue C<quota on -w volA> on the NetApp filer.
+
+=over 4
+
+=item B<Interval> I<Seconds>
+
+Collect SnapVault(R) statistics every I<Seconds> seconds.
+
+=back
+
+=head3 The SnapVault block
+
+This will collect statistics about the time and traffic of SnapVault(R)
+transfers.
+
+=over 4
+
+=item B<Interval> I<Seconds>
+
+Collect SnapVault(R) statistics every I<Seconds> seconds.
+
+=back
+
 =head2 Plugin C<netlink>
 
 The C<netlink> plugin uses a netlink socket to query the Linux kernel about
@@ -2664,10 +3108,18 @@ The default IPv6 multicast group is C<ff18::efc0:4a42>. The default IPv4
 multicast group is C<239.192.74.66>. The default I<UDP> port is B<25826>.
 
 Both, B<Server> and B<Listen> can be used as single option or as block. When
-used as block, given options are valid for this socket only. For example:
+used as block, given options are valid for this socket only. The following
+example will export the metrics twice: Once to an "internal" server (without
+encryption and signing) and one to an external server (with cryptographic
+signature):
 
  <Plugin "network">
+   # Export to an internal server
+   # (demonstrates usage without additional options)
    Server "collectd.internal.tld"
+   
+   # Export to an external server
+   # (demonstrates usage with signature options)
    <Server "collectd.external.tld">
      SecurityLevel "sign"
      Username "myhostname"
@@ -2975,6 +3427,16 @@ IP-address may be used in a filename it is recommended to disable reverse
 lookups. The default is to do reverse lookups to preserve backwards
 compatibility, though.
 
+=item B<IncludeUnitID> B<true>|B<false>
+
+When a peer is a refclock, include the unit ID in the I<type instance>.
+Defaults to B<false> for backward compatibility.
+
+If two refclock peers use the same driver and this is B<false>, the plugin will
+try to write simultaneous measurements from both to the same type instance.
+This will result in error messages in the log and only one set of measurements
+making it through.
+
 =back
 
 =head2 Plugin C<nut>
@@ -3200,6 +3662,11 @@ values submitted to the daemon. Other than that, that name is not used.
 Defines the "database alias" or "service name" to connect to. Usually, these
 names are defined in the file named C<$ORACLE_HOME/network/admin/tnsnames.ora>.
 
+=item B<Host> I<Host>
+
+Hostname to use when dispatching values for this database. Defaults to using
+the global hostname of the I<collectd> instance.
+
 =item B<Username> I<Username>
 
 Username used for authentication.
@@ -3377,6 +3844,13 @@ which are available in a PostgreSQL database or use future or special
 statistics provided by PostgreSQL without the need to upgrade your collectd
 installation.
 
+Starting with version 5.2, the C<postgresql> plugin supports writing data to
+PostgreSQL databases as well. This has been implemented in a generic way. You
+need to specify an SQL statement which will then be executed by collectd in
+order to write the data (see below for details). The benefit of that approach
+is that there is no fixed database layout. Rather, the layout may be optimized
+for the current setup.
+
 The B<PostgreSQL Documentation> manual can be found at
 L<http://www.postgresql.org/docs/manuals/>.
 
@@ -3406,6 +3880,11 @@ L<http://www.postgresql.org/docs/manuals/>.
       </Result>
     </Query>
 
+    <Writer sqlstore>
+      Statement "SELECT collectd_insert($1, $2, $3, $4, $5, $6, $7, $8, $9);"
+      StoreRates true
+    </Writer>
+
     <Database foo>
       Host "hostname"
       Port "5432"
@@ -3422,6 +3901,12 @@ L<http://www.postgresql.org/docs/manuals/>.
       Query backend # predefined
       Query rt36_tickets
     </Database>
+
+    <Database qux>
+      # ...
+      Writer sqlstore
+      CommitInterval 10
+    </Database>
   </Plugin>
 
 The B<Query> block defines one database query which may later be used by a
@@ -3470,6 +3955,11 @@ used, the parameter expands to "localhost".
 
 The name of the database of the current connection.
 
+=item I<instance>
+
+The name of the database plugin instance. See the B<Instance> option of the
+database specification below for details.
+
 =item I<username>
 
 The username used to connect to the database.
@@ -3583,6 +4073,101 @@ This query collects the on-disk size of the database in bytes.
 
 =back
 
+In addition, the following detailed queries are available by default. Please
+note that each of those queries collects information B<by table>, thus,
+potentially producing B<a lot> of data. For details see the description of the
+non-by_table queries above.
+
+=over 4
+
+=item B<queries_by_table>
+
+=item B<query_plans_by_table>
+
+=item B<table_states_by_table>
+
+=item B<disk_io_by_table>
+
+=back
+
+The B<Writer> block defines a PostgreSQL writer backend. It accepts a single
+mandatory argument specifying the name of the writer. This will then be used
+in the B<Database> specification in order to activate the writer instance. The
+names of all writers have to be unique. The following options may be
+specified:
+
+=over 4
+
+=item B<Statement> I<sql statement>
+
+This mandatory option specifies the SQL statement that will be executed for
+each submitted value. A single SQL statement is allowed only. Anything after
+the first semicolon will be ignored.
+
+Nine parameters will be passed to the statement and should be specified as
+tokens B<$1>, B<$2>, through B<$9> in the statement string. The following
+values are made available through those parameters:
+
+=over 4
+
+=item B<$1>
+
+The timestamp of the queried value as a floating point number.
+
+=item B<$2>
+
+The hostname of the queried value.
+
+=item B<$3>
+
+The plugin name of the queried value.
+
+=item B<$4>
+
+The plugin instance of the queried value. This value may be B<NULL> if there
+is no plugin instance.
+
+=item B<$5>
+
+The type of the queried value (cf. L<types.db(5)>).
+
+=item B<$6>
+
+The type instance of the queried value. This value may be B<NULL> if there is
+no type instance.
+
+=item B<$7>
+
+An array of names for the submitted values (i.E<nbsp>e., the name of the data
+sources of the submitted value-list).
+
+=item B<$8>
+
+An array of types for the submitted values (i.E<nbsp>e., the type of the data
+sources of the submitted value-list; C<counter>, C<gauge>, ...). Note, that if
+B<StoreRates> is enabled (which is the default, see below), all types will be
+C<gauge>.
+
+=item B<$9>
+
+An array of the submitted values. The dimensions of the value name and value
+arrays match.
+
+=back
+
+In general, it is advisable to create and call a custom function in the
+PostgreSQL database for this purpose. Any procedural language supported by
+PostgreSQL will do (see chapter "Server Programming" in the PostgreSQL manual
+for details).
+
+=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<nbsp>e. as an increasing integer
+number.
+
+=back
+
 The B<Database> block defines one PostgreSQL database for which to collect
 statistics. It accepts a single mandatory argument which specifies the
 database name. None of the other options are required. PostgreSQL will use
@@ -3598,6 +4183,17 @@ for details.
 Specify the interval with which the database should be queried. The default is
 to use the global B<Interval> setting.
 
+=item B<CommitInterval> I<seconds>
+
+This option may be used for database connections which have "writers" assigned
+(see above). If specified, it causes a writer to put several updates into a
+single transaction. This transaction will last for the specified amount of
+time. By default, each update will be executed in a separate transaction. Each
+transaction generates a fair amount of overhead which can, thus, be reduced by
+activating this option. The draw-back is, that data covering the specified
+amount of time will be lost, for example, if a single statement within the
+transaction fails or if the database server crashes.
+
 =item B<Host> I<hostname>
 
 Specify the hostname or IP of the PostgreSQL server to connect to. If the
@@ -3628,6 +4224,13 @@ Specify the password to be used when connecting to the server.
 Specify whether to use an SSL connection when contacting the server. The
 following modes are supported:
 
+=item B<Instance> I<name>
+
+Specify the plugin instance name that should be used instead of the database
+name (which is the default, if this option has not been specified). This
+allows to query multiple databases of the same name on the same host (e.g.
+when running multiple database server versions in parallel).
+
 =over 4
 
 =item I<disable>
@@ -3663,11 +4266,36 @@ B<PostgreSQL Documentation> for details.
 
 =item B<Query> I<query>
 
-Specify a I<query> which should be executed for the database connection. This
-may be any of the predefined or user-defined queries. If no such option is
-given, it defaults to "backends", "transactions", "queries", "query_plans",
-"table_states", "disk_io" and "disk_usage". Else, the specified queries are
-used only.
+Specifies a I<query> which should be executed in the context of the database
+connection. This may be any of the predefined or user-defined queries. If no
+such option is given, it defaults to "backends", "transactions", "queries",
+"query_plans", "table_states", "disk_io" and "disk_usage" (unless a B<Writer>
+has been specified). Else, the specified queries are used only.
+
+=item B<Writer> I<writer>
+
+Assigns the specified I<writer> backend to the database connection. This
+causes all collected data to be send to the database using the settings
+defined in the writer configuration (see the section "FILTER CONFIGURATION"
+below for details on how to selectively send data to certain plugins).
+
+Each writer will register a flush callback which may be used when having long
+transactions enabled (see the B<CommitInterval> option above). When issuing
+the B<FLUSH> command (see L<collectd-unixsock(5)> for details) the current
+transaction will be committed right away. Two different kinds of flush
+callbacks are available with the C<postgresql> plugin:
+
+=over 4
+
+=item B<postgresql>
+
+Flush all writer backends.
+
+=item B<postgresql->I<database>
+
+Flush all writers of the specified I<database> only.
+
+=back
 
 =back
 
@@ -3988,6 +4616,10 @@ The B<Port> option is the TCP port on which the Redis instance accepts
 connections. Either a service name of a port number may be given. Please note
 that numerical port numbers must be given as a string, too.
 
+=item B<Password> I<Password>
+
+Use I<Password> to authenticate when connecting to I<Redis>.
+
 =item B<Timeout> I<Timeout in miliseconds>
 
 The B<Timeout> option set the socket timeout for node response. Since the Redis
@@ -4045,6 +4677,60 @@ Enables or disables the creation of RRD files. If the daemon is not running
 locally, or B<DataDir> is set to a relative path, this will not work as
 expected. Default is B<true>.
 
+=item B<CreateFilesAsync> B<false>|B<true>
+
+When enabled, new RRD files are enabled asynchronously, using a separate thread
+that runs in the background. This prevents writes to block, which is a problem
+especially when many hundreds of files need to be created at once. However,
+since the purpose of creating the files asynchronously is I<not> to block until
+the file is available, values before the file is available will be discarded.
+When disabled (the default) files are created synchronously, blocking for a
+short while, while the file is being written.
+
+=item B<StepSize> I<Seconds>
+
+B<Force> the stepsize of newly created RRD-files. Ideally (and per default)
+this setting is unset and the stepsize is set to the interval in which the data
+is collected. Do not use this option unless you absolutely have to for some
+reason. Setting this option may cause problems with the C<snmp plugin>, the
+C<exec plugin> or when the daemon is set up to receive data from other hosts.
+
+=item B<HeartBeat> I<Seconds>
+
+B<Force> the heartbeat of newly created RRD-files. This setting should be unset
+in which case the heartbeat is set to twice the B<StepSize> which should equal
+the interval in which data is collected. Do not set this option unless you have
+a very good reason to do so.
+
+=item B<RRARows> I<NumRows>
+
+The C<rrdtool plugin> calculates the number of PDPs per CDP based on the
+B<StepSize>, this setting and a timespan. This plugin creates RRD-files with
+three times five RRAs, i. e. five RRAs with the CFs B<MIN>, B<AVERAGE>, and
+B<MAX>. The five RRAs are optimized for graphs covering one hour, one day, one
+week, one month, and one year.
+
+So for each timespan, it calculates how many PDPs need to be consolidated into
+one CDP by calculating:
+  number of PDPs = timespan / (stepsize * rrarows)
+
+Bottom line is, set this no smaller than the width of you graphs in pixels. The
+default is 1200.
+
+=item B<RRATimespan> I<Seconds>
+
+Adds an RRA-timespan, given in seconds. Use this option multiple times to have
+more then one RRA. If this option is never used, the built-in default of (3600,
+86400, 604800, 2678400, 31622400) is used.
+
+For more information on how RRA-sizes are calculated see B<RRARows> above.
+
+=item B<XFF> I<Factor>
+
+Set the "XFiles Factor". The default is 0.1. If unsure, don't set this option.
+I<Factor> must be in the range C<[0.0-1.0)>, i.e. between zero (inclusive) and
+one (exclusive).
+
 =back
 
 =head2 Plugin C<rrdtool>
@@ -4058,8 +4744,18 @@ can safely ignore these settings.
 
 =item B<DataDir> I<Directory>
 
-Set the directory to store RRD-files under. Per default RRD-files are generated
-beneath the daemon's working directory, i.E<nbsp>e. the B<BaseDir>.
+Set the directory to store RRD files under. By default RRD files are generated
+beneath the daemon's working directory, i.e. the B<BaseDir>.
+
+=item B<CreateFilesAsync> B<false>|B<true>
+
+When enabled, new RRD files are enabled asynchronously, using a separate thread
+that runs in the background. This prevents writes to block, which is a problem
+especially when many hundreds of files need to be created at once. However,
+since the purpose of creating the files asynchronously is I<not> to block until
+the file is available, values before the file is available will be discarded.
+When disabled (the default) files are created synchronously, blocking for a
+short while, while the file is being written.
 
 =item B<StepSize> I<Seconds>
 
@@ -4080,7 +4776,7 @@ a very good reason to do so.
 
 The C<rrdtool plugin> calculates the number of PDPs per CDP based on the
 B<StepSize>, this setting and a timespan. This plugin creates RRD-files with
-three times five RRAs, i. e. five RRAs with the CFs B<MIN>, B<AVERAGE>, and
+three times five RRAs, i.e. five RRAs with the CFs B<MIN>, B<AVERAGE>, and
 B<MAX>. The five RRAs are optimized for graphs covering one hour, one day, one
 week, one month, and one year.
 
@@ -4102,6 +4798,8 @@ For more information on how RRA-sizes are calculated see B<RRARows> above.
 =item B<XFF> I<Factor>
 
 Set the "XFiles Factor". The default is 0.1. If unsure, don't set this option.
+I<Factor> must be in the range C<[0.0-1.0)>, i.e. between zero (inclusive) and
+one (exclusive).
 
 =item B<CacheFlush> I<Seconds>
 
@@ -4217,6 +4915,11 @@ and available space of each device will be reported separately.
 This option is only available if the I<Swap plugin> can read C</proc/swaps>
 (under Linux) or use the L<swapctl(2)> mechanism (under I<Solaris>).
 
+=item B<ReportBytes> B<false>|B<true>
+
+When enabled, the I<swap I/O> is reported in bytes. When disabled, the default,
+I<swap I/O> is reported in pages. This option is available under Linux only.
+
 =back
 
 =head2 Plugin C<syslog>
@@ -4469,6 +5172,97 @@ This optional setting sets the type instance to use.
 
 =back
 
+=head2 Plugin C<tail_csv>
+
+The I<tail_csv plugin> reads files in the CSV format, e.g. the statistics file
+written by I<Snort>.
+
+B<Synopsis:>
+
+ <Plugin "tail_csv">
+   <Metric "snort-dropped">
+       Type "percent"
+       Instance "dropped"
+       Index 1
+   </Metric>
+   <File "/var/log/snort/snort.stats">
+       Instance "snort-eth0"
+       Interval 600
+       Collect "snort-dropped"
+   </File>
+ </Plugin>
+
+The configuration consists of one or more B<Metric> blocks that define an index
+into the line of the CSV file and how this value is mapped to I<collectd's>
+internal representation. These are followed by one or more B<Instance> blocks
+which configure which file to read, in which interval and which metrics to
+extract.
+
+=over 4
+
+=item E<lt>B<Metric> I<Name>E<gt>
+
+The B<Metric> block configures a new metric to be extracted from the statistics
+file and how it is mapped on I<collectd's> data model. The string I<Name> is
+only used inside the B<Instance> blocks to refer to this block, so you can use
+one B<Metric> block for multiple CSV files.
+
+=over 4
+
+=item B<Type> I<Type>
+
+Configures which I<Type> to use when dispatching this metric. Types are defined
+in the L<types.db(5)> file, see the appropriate manual page for more
+information on specifying types. Only types with a single I<data source> are
+supported by the I<tail_csv plugin>. The information whether the value is an
+absolute value (i.e. a C<GAUGE>) or a rate (i.e. a C<DERIVE>) is taken from the
+I<Type's> definition.
+
+=item B<Instance> I<TypeInstance>
+
+If set, I<TypeInstance> is used to populate the type instance field of the
+created value lists. Otherwise, no type instance is used.
+
+=item B<ValueFrom> I<Index>
+
+Configure to read the value from the field with the zero-based index I<Index>.
+If the value is parsed as signed integer, unsigned integer or double depends on
+the B<Type> setting, see above.
+
+=back
+
+=item E<lt>B<File> I<Path>E<gt>
+
+Each B<File> block represents one CSV file to read. There must be at least one
+I<File> block but there can be multiple if you have multiple CSV files.
+
+=over 4
+
+=item B<Instance> I<PluginInstance>
+
+Sets the I<plugin instance> used when dispatching the values.
+
+=item B<Collect> I<Metric>
+
+Specifies which I<Metric> to collect. This option must be specified at least
+once, and you can use this option multiple times to specify more than one
+metric to be extracted from this statistic file.
+
+=item B<Interval> I<Seconds>
+
+Configures the interval in which to read values from this instance / file.
+Defaults to the plugin's default interval.
+
+=item B<TimeFrom> I<Index>
+
+Rather than using the local time when dispatching a value, read the timestamp
+from the field with the zero-based index I<Index>. The value is interpreted as
+seconds since epoch. The value is parsed as a double and may be factional.
+
+=back
+
+=back
+
 =head2 Plugin C<teamspeak2>
 
 The C<teamspeak2 plugin> connects to the query port of a teamspeak2 server and
@@ -4697,7 +5491,33 @@ Take the UUID from the given file (default I</etc/uuid>).
 
 =head2 Plugin C<varnish>
 
-The Varnish plugin collects information about Varnish, an HTTP accelerator.
+The I<varnish plugin> collects information about Varnish, an HTTP accelerator.
+
+Synopsis:
+
+ <Plugin "varnish">
+   <Instance "example">
+     CollectCache       true
+     CollectConnections true
+     CollectBackend     true
+     CollectSHM         true
+     CollectESI         false
+     CollectFetch       false
+     CollectHCB         false
+     CollectSMA         false
+     CollectSMS         false
+     CollectSM          false
+     CollectTotals      false
+     CollectWorkers     false
+   </Instance>
+ </Plugin>
+
+The configuration consists of one or more E<lt>B<Instance>E<nbsp>I<Name>E<gt>
+blocks. I<Name> is the parameter passed to "varnishd -n". If left empty, it
+will collectd statistics from the default "varnishd" instance (this should work
+fine in most cases).
+
+Inside each E<lt>B<Instance>E<gt> blocks, the following options are recognized:
 
 =over 4
 
@@ -4802,13 +5622,16 @@ minimize the number of network packets.
 Synopsis:
 
  <Plugin write_graphite>
-   <Carbon>
+   <Node "example">
      Host "localhost"
      Port "2003"
      Prefix "collectd"
-   </Carbon>
+   </Node>
  </Plugin>
 
+The configuration consists of one or more E<lt>B<Node>E<nbsp>I<Name>E<gt>
+blocks. Inside the B<Node> blocks, the following options are recognized:
+
 =over 4
 
 =item B<Host> I<Address>
@@ -4847,7 +5670,7 @@ number.
 If set to B<true>, the plugin instance and type instance will be in their own
 path component, for example C<host.cpu.0.cpu.idle>. If set to B<false> (the
 default), the plugin and plugin instance (and likewise the type and type
-instance) are put into once component, for example C<host.cpu-0.cpu-idle>.
+instance) are put into one component, for example C<host.cpu-0.cpu-idle>.
 
 =item B<AlwaysAppendDS> B<false>|B<true>
 
@@ -4857,6 +5680,59 @@ more than one DS.
 
 =back
 
+=head2 Plugin C<write_mongodb>
+
+The I<write_mongodb plugin> will send values to I<MongoDB>, a schema-less
+NoSQL database.
+
+B<Synopsis:>
+
+ <Plugin "write_mongodb">
+   <Node "default">
+     Host "localhost"
+     Port "27017"
+     Timeout 1000
+     StoreRates true
+   </Node>
+ </Plugin>
+
+The plugin can send values to multiple instances of I<MongoDB> by specifying
+one B<Node> block for each instance. Within the B<Node> blocks, the following
+options are available:
+
+=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<27017>.
+
+=item B<Timeout> I<Timeout>
+
+Set the timeout for each operation on I<MongoDB> to I<Timeout> milliseconds.
+Setting this option to zero means no timeout, which is the default.
+
+=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.
+
+=item B<Database> I<Database>
+
+=item B<User> I<User>
+
+=item B<Password> I<Password>
+
+Sets the information used when authenticating to a I<MongoDB> database. The
+fields are optional (in which case no authentication is attempted), but if you
+want to use authentication all three fields must be set.
+
+=back
+
 =head2 Plugin C<write_http>
 
 This output plugin submits values to an http server by POST them using the
@@ -4921,6 +5797,241 @@ number.
 
 =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"
+     Protocol UDP
+     StoreRates true
+     AlwaysAppendDS 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<Protocol> B<UDP>|B<TCP>
+
+Specify the protocol to use when communicating with I<Riemann>. Defaults to
+B<UDP>.
+
+=item B<StoreRates> B<true>|B<false>
+
+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
+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.
+
+ <Plugin 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>
+   </Host>
+ </Plugin>
+
+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<Number>
+
+Delay creating the notification until the threshold has been passed I<Number>
+times. When a notification has been generated, or when a subsequent value is
+inside the threshold, the counter is reset. If, for example, a value is
+collected once every 10E<nbsp>seconds and B<Hits> is set to 3, a notification
+will be dispatched at most once every 30E<nbsp>seconds.
+
+This is useful when short bursts are not a problem. If, for example, 100% CPU
+usage for up to a minute is normal (and data is collected every
+10E<nbsp>seconds), you could set B<Hits> to B<6> to account for this.
+
+=item B<Hysteresis> I<Number>
+
+When set to non-zero, a hysteresis value is applied when checking minimum and
+maximum bounds. This is useful for values that increase slowly and fluctuate a
+bit while doing so. When these values come close to the threshold, they may
+"flap", i.e. switch between failure / warning case and okay case repeatedly.
+
+If, for example, the threshold is configures as
+
+  WarningMax 100.0
+  Hysteresis 1.0
+
+then a I<Warning> notification is created when the value exceeds I<101> and the
+corresponding I<Okay> notification is only created once the value falls below
+I<99>, thus avoiding the "flapping".
+
+=back
+
 =head1 FILTER CONFIGURATION
 
 Starting with collectd 4.6 there is a powerful filtering infrastructure