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<MeasureResponseTime> B<true>|B<false>
+
+Measure response time for the request. Disabled by default.
+
=item B<E<lt>MatchE<gt>>
One or more B<Match> blocks that define how to match information in the data
=back
+=head2 Plugin C<curl_json>
+
+The B<curl_json plugin> uses B<libcurl> (L<http://curl.haxx.se/>) and
+B<libyajl> (L<http://www.lloydforge.org/projects/yajl/>) to retrieve JSON data
+via cURL. This can be used to collect values from CouchDB documents (which are
+stored JSON notation), for example.
+
+The following example will collect several values from the built-in `_stats'
+runtime statistics module of CouchDB
+(L<http://wiki.apache.org/couchdb/Runtime_Statistics>).
+
+ <Plugin curl_json>
+ <URL "http://localhost:5984/_stats">
+ Instance "httpd"
+ <Key "httpd/requests/count">
+ Type "http_requests"
+ </Key>
+
+ <Key "httpd_request_methods/*/count">
+ Type "http_request_methods"
+ </Key>
+
+ <Key "httpd_status_codes/*/count">
+ Type "http_response_codes"
+ </Key>
+ </URL>
+ </Plugin>
+
+Another CouchDB example:
+The following example will collect the status values from each database:
+
+ <URL "http://localhost:5984/_all_dbs">
+ Instance "dbs"
+ <Key "*/doc_count">
+ Type "gauge"
+ </Key>
+ <Key "*/doc_del_count">
+ Type "counter"
+ </Key>
+ <Key "*/disk_size">
+ Type "bytes"
+ </Key>
+ </URL>
+
+In the B<Plugin> block, there may be one or more B<URL> blocks, each defining
+a URL to be fetched via HTTP (using libcurl) and one or more B<Key> blocks.
+The B<Key> string argument must be in a path format, of which is used to collect
+a value from a JSON map object. If a B<Key> path element is that of a I<*> wildcard,
+the values for all keys will be collectd.
+
+The following options are valid within B<URL> blocks:
+
+=over 4
+
+=item B<Instance> I<Instance>
+
+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>
+
+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.
+
+=back
+
+The following options are valid within B<Key> blocks:
+
+=over 4
+
+=item B<Type> I<Type>
+
+Sets the type used to dispatch the values to the daemon. Detailed information
+about types and their configuration can be found in L<types.db(5)>. This
+option is mandatory.
+
+=item B<Instance> I<Instance>
+
+Type-instance to use. Defaults to the current map key or current string array element value.
+
+=back
+
=head2 Plugin C<dbi>
This plugin uses the B<dbi> library (L<http://libdbi.sourceforge.net/>) to
Specifies the columns whose values will be used to create the "type-instance"
for each row. If you specify more than one column, the value of all columns
-will be join together with the dashes I<("-")> as separation character.
+will be joined together with dashes I<("-")> as separation characters.
The plugin itself does not check whether or not all built instances are
different. It's your responsibility to assure that each is unique. This is
Select partitions based on the filesystem type.
-=item B<IgnoreSelected> I<true>|I<false>
+=item B<IgnoreSelected> B<true>|B<false>
Invert the selection: If set to true, all partitions B<except> the ones that
match any one of the criteria are collected. By default only selected
partitions are collected if a selection is made. If no selection is configured
at all, B<all> partitions are selected.
+=item B<ReportByDevice> B<true>|B<false>
+
+Report using the device name rather than the mountpoint. i.e. with this I<false>,
+(the default), it will report a disk as "root", but with it I<true>, it will be
+"sda1" (or whichever).
+
+=item B<ReportReserved> B<true>|B<false>
+
+When enabled, the blocks reserved for root are reported separately. When
+disabled (the default for backwards compatibility reasons) the reserved space
+will be included in the "free" space.
+
+When disabled, the "df" type will be used to store "free" and "used" space. The
+mount point or disk name (see option B<ReportByDevice>) is used as type
+instance in this case (again: backwards compatibility).
+
+When enabled, the type "df_complex" is used and three files are created. The
+mount point or disk name is used as plugin instance and the type instance is
+set to "free", "reserved" and "used" as appropriate.
+
+Enabling this option is recommended.
+
+=item B<ReportInodes> B<true>|B<false>
+
+Enables or disables reporting of free, reserved and used inodes. Defaults to
+inode collection being disabled.
+
+Enable this option if inodes are a scarce resource for you, usually because
+many small files are stored on the disk. This is a usual scenario for mail
+transfer agents and web caches.
+
=back
=head2 Plugin C<disk>
Ignore packets that originate from this address.
+=item B<SelectNumericQueryTypes> B<true>|B<false>
+
+Enabled by default, collects unknown (and thus presented as numeric only) query types.
+
=back
=head2 Plugin C<email>
=back
+=head2 Plugin C<GenericJMX>
+
+The I<GenericJMX plugin> is written in I<Java> and therefore documented in
+L<collectd-java(5)>.
+
+=head2 Plugin C<gmond>
+
+The I<gmond> plugin received the multicast traffic sent by B<gmond>, the
+statistics collection daemon of Ganglia. Mappings for the standard "metrics"
+are built-in, custom mappings may be added via B<Metric> blocks, see below.
+
+Synopsis:
+
+ <Plugin "gmond">
+ MCReceiveFrom "239.2.11.71" "8649"
+ <Metric "swap_total">
+ Type "swap"
+ TypeInstance "total"
+ DataSource "value"
+ </Metric>
+ <Metric "swap_free">
+ Type "swap"
+ TypeInstance "free"
+ DataSource "value"
+ </Metric>
+ </Plugin>
+
+The following metrics are built-in:
+
+=over 4
+
+=item *
+
+load_one, load_five, load_fifteen
+
+=item *
+
+cpu_user, cpu_system, cpu_idle, cpu_nice, cpu_wio
+
+=item *
+
+mem_free, mem_shared, mem_buffers, mem_cached, mem_total
+
+=item *
+
+bytes_in, bytes_out
+
+=item *
+
+pkts_in, pkts_out
+
+=back
+
+Available configuration options:
+
+=over 4
+
+=item B<MCReceiveFrom> I<MCGroup> [I<Port>]
+
+Sets sets the multicast group and UDP port to which to subscribe.
+
+Default: B<239.2.11.71>E<nbsp>/E<nbsp>B<8649>
+
+=item E<lt>B<Metric> I<Name>E<gt>
+
+These blocks add a new metric conversion to the internal table. I<Name>, the
+string argument to the B<Metric> block, is the metric name as used by Ganglia.
+
+=over 4
+
+=item B<Type> I<Type>
+
+Type to map this metric to. Required.
+
+=item B<TypeInstance> I<Instance>
+
+Type-instance to use. Optional.
+
+=item B<DataSource> I<Name>
+
+Data source to map this metric to. If the configured type has exactly one data
+source, this is optional. Otherwise the option is required.
+
+=back
+
+=back
+
=head2 Plugin C<hddtemp>
To get values from B<hddtemp> collectd connects to B<localhost> (127.0.0.1),
=back
+=head2 Plugin C<java>
+
+The I<Java> plugin makes it possible to write extensions for collectd in Java.
+This section only discusses the syntax and semantic of the configuration
+options. For more in-depth information on the I<Java> plugin, please read
+L<collectd-java(5)>.
+
+Synopsis:
+
+ <Plugin "java">
+ JVMArg "-verbose:jni"
+ JVMArg "-Djava.class.path=/opt/collectd/lib/collectd/bindings/java"
+ LoadPlugin "org.collectd.java.Foobar"
+ <Plugin "org.collectd.java.Foobar">
+ # To be parsed by the plugin
+ </Plugin>
+ </Plugin>
+
+Available configuration options:
+
+=over 4
+
+=item B<JVMArg> I<Argument>
+
+Argument that is to be passed to the I<Java Virtual Machine> (JVM). This works
+exactly the way the arguments to the I<java> binary on the command line work.
+Execute C<javaE<nbsp>--help> for details.
+
+Please note that B<all> these options must appear B<before> (i.E<nbsp>e. above)
+any other options! When another option is found, the JVM will be started and
+later options will have to be ignored!
+
+=item B<LoadPlugin> I<JavaClass>
+
+Instantiates a new I<JavaClass> object. The constructor of this object very
+likely then registers one or more callback methods with the server.
+
+See L<collectd-java(5)> for details.
+
+When the first such option is found, the virtual machine (JVM) is created. This
+means that all B<JVMArg> options must appear before (i.E<nbsp>e. above) all
+B<LoadPlugin> options!
+
+=item B<Plugin> I<Name>
+
+The entire block is passed to the Java plugin as an
+I<org.collectd.api.OConfigItem> object.
+
+For this to work, the plugin has to register a configuration callback first,
+see L<collectd-java(5)/"config callback">. This means, that the B<Plugin> block
+must appear after the appropriate B<LoadPlugin> block. Also note, that I<Name>
+depends on the (Java) plugin registering the callback and is completely
+independent from the I<JavaClass> argument passed to B<LoadPlugin>.
+
+=back
+
=head2 Plugin C<libvirt>
This plugin allows CPU, disk and network load to be collected for virtualized
=back
+=head2 Plugin C<memcachec>
+
+The C<memcachec plugin> connects to a memcached server, queries one or more
+given I<pages> and parses the returned data according to user specification.
+The I<matches> used are the same as the matches used in the C<curl> and C<tail>
+plugins.
+
+In order to talk to the memcached server, this plugin uses the I<libmemcached>
+library. Please note that there is another library with a very similar name,
+libmemcache (notice the missing `d'), which is not applicable.
+
+Synopsis of the configuration:
+
+ <Plugin "memcachec">
+ <Page "plugin_instance">
+ Server "localhost"
+ Key "page_key"
+ <Match>
+ Regex "(\\d+) bytes sent"
+ DSType CounterAdd
+ Type "ipt_octets"
+ Instance "type_instance"
+ </Match>
+ </Page>
+ </Plugin>
+
+The configuration options are:
+
+=over 4
+
+=item E<lt>B<Page> I<Name>E<gt>
+
+Each B<Page> block defines one I<page> to be queried from the memcached server.
+The block requires one string argument which is used as I<plugin instance>.
+
+=item B<Server> I<Address>
+
+Sets the server address to connect to when querying the page. Must be inside a
+B<Page> block.
+
+=item B<Key> I<Key>
+
+When connected to the memcached server, asks for the page I<Key>.
+
+=item E<lt>B<Match>E<gt>
+
+Match blocks define which strings to look for and how matches substrings are
+interpreted. For a description of match blocks, please see L<"Plugin tail">.
+
+=back
+
=head2 Plugin C<memcached>
The C<memcached plugin> connects to a memcached server and queries statistics
=head2 Plugin C<mysql>
-The C<mysql plugin> requires B<mysqlclient> to be installed. It connects to the
-database when started and keeps the connection up as long as possible. When the
-connection is interrupted for whatever reason it will try to re-connect. The
-plugin will complaint loudly in case anything goes wrong.
+The C<mysql plugin> requires B<mysqlclient> to be installed. It connects to
+one or more databases when started and keeps the connection up as long as
+possible. When the connection is interrupted for whatever reason it will try
+to re-connect. The plugin will complaint loudly in case anything goes wrong.
+
+This plugin issues the MySQL C<SHOW STATUS> / C<SHOW GLOBAL STATUS> command
+and collects information about MySQL network traffic, executed statements,
+requests, the query cache and threads by evaluating the
+C<Bytes_{received,sent}>, C<Com_*>, C<Handler_*>, C<Qcache_*> and C<Threads_*>
+return values. Please refer to the B<MySQL reference manual>, I<5.1.6. Server
+Status Variables> for an explanation of these values.
+
+Optionally, master and slave statistics may be collected in a MySQL
+replication setup. In that case, information about the synchronization state
+of the nodes are collected by evaluating the C<Position> return value of the
+C<SHOW MASTER STATUS> command and the C<Seconds_Behind_Master>,
+C<Read_Master_Log_Pos> and C<Exec_Master_Log_Pos> return values of the
+C<SHOW SLAVE STATUS> command. See the B<MySQL reference manual>,
+I<12.5.5.21 SHOW MASTER STATUS Syntax> and
+I<12.5.5.31 SHOW SLAVE STATUS Syntax> for details.
+
+Synopsis:
-This plugin issues the MySQL C<SHOW STATUS> command and collects information
-about MySQL network traffic, executed statements, requests, the query cache
-and threads by evaluating the C<Bytes_{received,sent}>, C<Com_*>,
-C<Handler_*>, C<Qcache_*> and C<Threads_*> return values. Please refer to the
-B<MySQL reference manual>, I<5.1.6. Server Status Variables> for an
-explanation of these values.
+ <Plugin mysql>
+ <Database foo>
+ Host "hostname"
+ User "username"
+ Password "password"
+ Port "3306"
+ MasterStats true
+ </Database>
+
+ <Database bar>
+ Host "localhost"
+ Socket "/var/run/mysql/mysqld.sock"
+ SlaveStats true
+ SlaveNotifications true
+ </Database>
+ </Plugin>
-Use the following options to configure the plugin:
+A B<Database> block defines one connection to a MySQL database. It accepts a
+single argument which specifies the name of the database. None of the other
+options are required. MySQL will use default values as documented in the
+section "mysql_real_connect()" in the B<MySQL reference manual>.
=over 4
Otherwise, use the B<Port> option above. See the documentation for the
C<mysql_real_connect> function for details.
+=item B<MasterStats> I<true|false>
+
+=item B<SlaveStats> I<true|false>
+
+Enable the collection of master / slave statistics in a replication setup.
+
+=item B<SlaveNotifications> I<true|false>
+
+If enabled, the plugin sends a notification if the replication slave I/O and /
+or SQL threads are not running.
+
+=back
+
+=head2 Plugin C<netapp>
+
+The netapp plugin can collect various performance and capacity informations
+from a NetApp filer using the NetApp API.
+
+To collect these data collectd will log in to the NetApp via HTTP(S) and HTTP
+basic authentication.
+
+B<Do not use a regular user for this!> Create a special collectd user with just
+the minimum of capabilities needed. The user only needs the "login-http-admin"
+capability as well as a few more depending on which data will be collected.
+Required capabilities are documented below.
+
+=head3 Synopsis
+
+ <Plugin "netapp">
+ <Host "netapp1.example.com">
+ Protocol "https"
+ Address "10.0.0.1"
+ Port 443
+ User "username"
+ Password "aef4Aebe"
+ Interval 30
+
+ <WAFL>
+ Interval 30
+ GetNameCache true
+ GetDirCache true
+ GetBufferCache true
+ GetInodeCache true
+ </WAFL>
+
+ <Disks>
+ Interval 30
+ GetBusy true
+ </Disks>
+
+ <VolumePerf>
+ Interval 30
+ GetIO "volume0"
+ IgnoreSelectedIO false
+ GetOps "volume0"
+ IgnoreSelectedOps false
+ GetLatency "volume0"
+ IgnoreSelectedLatency false
+ </VolumePerf>
+
+ <VolumeUsage>
+ Interval 30
+ GetCapacity "vol0"
+ GetCapacity "vol1"
+ IgnoreSelectedCapacity false
+ GetSnapshot "vol1"
+ GetSnapshot "vol3"
+ IgnoreSelectedSnapshot false
+ </VolumeUsage>
+
+ <System>
+ Interval 30
+ GetCPULoad true
+ GetInterfaces true
+ GetDiskOps true
+ GetDiskIO true
+ </System>
+ </Host>
+ </Plugin>
+
+The netapp plugin accepts the following configuration options:
+
+=over 4
+
+=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.
+
+=item B<Protocol> B<httpd>|B<http>
+
+The protocol collectd will use to query this host.
+
+Optional
+
+Type: string
+
+Default: https
+
+Valid options: http, https
+
+=item B<Address> I<Address>
+
+The hostname or IP address of the host.
+
+Optional
+
+Type: string
+
+Default: The "host" block's name.
+
+=item B<Port> I<Port>
+
+The TCP port to connect to on the host.
+
+Optional
+
+Type: integer
+
+Default: 80 for protocol "http", 443 for protocol "https"
+
+=item B<User> I<User>
+
+=item B<Password> I<Password>
+
+The username and password to use to login to the NetApp.
+
+Mandatory
+
+Type: string
+
+=item B<Interval> I<Interval>
+
+B<TODO>
+
+=back
+
+The following options decide what kind of data will be collected. You can
+either use them as a block and fine tune various parameters inside this block,
+use them as a single statement to just accept all default values, or omit it to
+not collect any data.
+
+The following options are valid inside all blocks:
+
+=over 4
+
+=item B<Interval> I<Seconds>
+
+Collect the respective statistics every I<Seconds> seconds. Defaults to the
+host specific setting.
+
+=back
+
+=head3 The System block
+
+This will collect various performance data about the whole system.
+
+B<Note:> To get this data the collectd user needs the
+"api-perf-object-get-instances" capability.
+
+=over 4
+
+=item B<Interval> I<Seconds>
+
+Collect disk statistics every I<Seconds> seconds.
+
+=item B<GetCPULoad> B<true>|B<false>
+
+If you set this option to true the current CPU usage will be read. This will be
+the average usage between all CPUs in your NetApp without any information about
+individual CPUs.
+
+B<Note:> These are the same values that the NetApp CLI command "sysstat"
+returns in the "CPU" field.
+
+Optional
+
+Type: boolean
+
+Default: true
+
+Result: Two value lists of type "cpu", and type instances "idle" and "system".
+
+=item B<GetInterfaces> B<true>|B<false>
+
+If you set this option to true the current traffic of the network interfaces
+will be read. This will be the total traffic over all interfaces of your NetApp
+without any information about individual interfaces.
+
+B<Note:> This is the same values that the NetApp CLI command "sysstat" returns
+in the "Net kB/s" field.
+
+B<Or is it?>
+
+Optional
+
+Type: boolean
+
+Default: true
+
+Result: One value list of type "if_octects".
+
+=item B<GetDiskIO> B<true>|B<false>
+
+If you set this option to true the current IO throughput will be read. This
+will be the total IO of your NetApp without any information about individual
+disks, volumes or aggregates.
+
+B<Note:> This is the same values that the NetApp CLI command "sysstat" returns
+in the "DiskE<nbsp>kB/s" field.
+
+Optional
+
+Type: boolean
+
+Default: true
+
+Result: One value list of type "disk_octets".
+
+=item B<GetDiskOps> B<true>|B<false>
+
+If you set this option to true the current number of HTTP, NFS, CIFS, FCP,
+iSCSI, etc. operations will be read. This will be the total number of
+operations on your NetApp without any information about individual volumes or
+aggregates.
+
+B<Note:> These are the same values that the NetApp CLI command "sysstat"
+returns in the "NFS", "CIFS", "HTTP", "FCP" and "iSCSI" fields.
+
+Optional
+
+Type: boolean
+
+Default: true
+
+Result: A variable number of value lists of type "disk_ops_complex". Each type
+of operation will result in one value list with the name of the operation as
+type instance.
+
+=back
+
+=head3 The WAFL block
+
+This will collect various performance data about the WAFL file system. At the
+moment this just means cache performance.
+
+B<Note:> To get this data the collectd user needs the
+"api-perf-object-get-instances" capability.
+
+B<Note:> The interface to get these values is classified as "Diagnostics" by
+NetApp. This means that it is not guaranteed to be stable even between minor
+releases.
+
+=over 4
+
+=item B<Interval> I<Seconds>
+
+Collect disk statistics every I<Seconds> seconds.
+
+=item B<GetNameCache> B<true>|B<false>
+
+Optional
+
+Type: boolean
+
+Default: true
+
+Result: One value list of type "cache_ratio" and type instance
+"name_cache_hit".
+
+=item B<GetDirCache> B<true>|B<false>
+
+Optional
+
+Type: boolean
+
+Default: true
+
+Result: One value list of type "cache_ratio" and type instance "find_dir_hit".
+
+=item B<GetInodeCache> B<true>|B<false>
+
+Optional
+
+Type: boolean
+
+Default: true
+
+Result: One value list of type "cache_ratio" and type instance
+"inode_cache_hit".
+
+=item B<GetBufferCache> B<true>|B<false>
+
+B<Note:> This is the same value that the NetApp CLI command "sysstat" returns
+in the "Cache hit" field.
+
+Optional
+
+Type: boolean
+
+Default: true
+
+Result: One value list of type "cache_ratio" and type instance "buf_hash_hit".
+
+=back
+
+=head3 The Disks block
+
+This will collect performance data about the individual disks in the NetApp.
+
+B<Note:> To get this data the collectd user needs the
+"api-perf-object-get-instances" capability.
+
+=over 4
+
+=item B<Interval> I<Seconds>
+
+Collect disk statistics every I<Seconds> seconds.
+
+=item B<GetBusy> B<true>|B<false>
+
+If you set this option to true the busy time of all disks will be calculated
+and the value of the busiest disk in the system will be written.
+
+B<Note:> This is the same values that the NetApp CLI command "sysstat" returns
+in the "Disk util" field. Probably.
+
+Optional
+
+Type: boolean
+
+Default: true
+
+Result: One value list of type "percent" and type instance "disk_busy".
+
+=back
+
+=head3 The VolumePerf block
+
+This will collect various performance data about the individual volumes.
+
+You can select which data to collect about which volume using the following
+options. They follow the standard ignorelist semantic.
+
+B<Note:> To get this data the collectd user needs the
+I<api-perf-object-get-instances> capability.
+
+=over 4
+
+=item B<Interval> I<Seconds>
+
+Collect volume performance data every I<Seconds> seconds.
+
+=item B<GetIO> I<Volume>
+
+=item B<GetOps> I<Volume>
+
+=item B<GetLatency> I<Volume>
+
+Select the given volume for IO, operations or latency statistics collection.
+The argument is the name of the volume without the C</vol/> prefix.
+
+Since the standard ignorelist functionality is used here, you can use a string
+starting and ending with a slash to specify regular expression matching: To
+match the volumes "vol0", "vol2" and "vol7", you can use this regular
+expression:
+
+ GetIO "/^vol[027]$/"
+
+If no regular expression is specified, an exact match is required. Both,
+regular and exact matching are case sensitive.
+
+If no volume was specified at all for either of the three options, that data
+will be collected for all available volumes.
+
+=item B<IgnoreSelectedIO> B<true>|B<false>
+
+=item B<IgnoreSelectedOps> B<true>|B<false>
+
+=item B<IgnoreSelectedLatency> B<true>|B<false>
+
+When set to B<true>, the volumes selected for IO, operations or latency
+statistics collection will be ignored and the data will be collected for all
+other volumes.
+
+When set to B<false>, data will only be collected for the specified volumes and
+all other volumes will be ignored.
+
+If no volumes have been specified with the above B<Get*> options, all volumes
+will be collected regardless of the B<IgnoreSelected*> option.
+
+Defaults to B<false>
+
+=back
+
+=head3 The VolumeUsage block
+
+This will collect capacity data about the individual volumes.
+
+B<Note:> To get this data the collectd user needs the I<api-volume-list-info>
+capability.
+
+=over 4
+
+=item B<Interval> I<Seconds>
+
+Collect volume usage statistics every I<Seconds> seconds.
+
+=item B<GetCapacity> I<VolumeName>
+
+The current capacity of the volume will be collected. This will result in two
+to four value lists, depending on the configuration of the volume. All data
+sources are of type "df_complex" with the name of the volume as
+plugin_instance.
+
+There will be type_instances "used" and "free" for the number of used and
+available bytes on the volume. If the volume has some space reserved for
+snapshots, a type_instance "snap_reserved" will be available. If the volume
+has SIS enabled, a type_instance "sis_saved" will be available. This is the
+number of bytes saved by the SIS feature.
+
+B<Note:> The current NetApp API has a bug that results in this value being
+reported as a 32E<nbsp>bit number. This plugin tries to guess the correct
+number which works most of the time. If you see strange values here, bug
+NetApp support to fix this.
+
+Repeat this option to specify multiple volumes.
+
+=item B<IgnoreSelectedCapacity> B<true>|B<false>
+
+Specify whether to collect only the volumes selected by the B<GetCapacity>
+option or to ignore those volumes. B<IgnoreSelectedCapacity> defaults to
+B<false>. However, if no B<GetCapacity> option is specified at all, all
+capacities will be selected anyway.
+
+=item B<GetSnapshot> I<VolumeName>
+
+Select volumes from which to collect snapshot information.
+
+Usually, the space used for snapshots is included in the space reported as
+"used". If snapshot information is collected as well, the space used for
+snapshots is subtracted from the used space.
+
+To make things even more interesting, it is possible to reserve space to be
+used for snapshots. If the space required for snapshots is less than that
+reserved space, there is "reserved free" and "reserved used" space in addition
+to "free" and "used". If the space required for snapshots exceeds the reserved
+space, that part allocated in the normal space is subtracted from the "used"
+space again.
+
+Repeat this option to specify multiple volumes.
+
+=item B<IgnoreSelectedSnapshot>
+
+Specify whether to collect only the volumes selected by the B<GetSnapshot>
+option or to ignore those volumes. B<IgnoreSelectedSnapshot> defaults to
+B<false>. However, if no B<GetSnapshot> option is specified at all, all
+capacities will be selected anyway.
+
=back
=head2 Plugin C<netlink>
=head2 Plugin C<network>
+The Network plugin sends data to a remote instance of collectd, receives data
+from a remote instance, or both at the same time. Data which has been received
+from the network is usually not transmitted again, but this can be actived, see
+the B<Forward> option below.
+
+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:
+
+ <Plugin "network">
+ Server "collectd.internal.tld"
+ <Server "collectd.external.tld">
+ SecurityLevel "sign"
+ Username "myhostname"
+ Password "ohl0eQue"
+ </Server>
+ </Plugin>
+
+=over 4
+
+=item B<E<lt>Server> I<Host> [I<Port>]B<E<gt>>
+
+The B<Server> statement/block sets the server to send datagrams to. The
+statement may occur multiple times to send each datagram to multiple
+destinations.
+
+The argument I<Host> may be a hostname, an IPv4 address or an IPv6 address. The
+optional second argument specifies a port number or a service name. If not
+given, the default, B<25826>, is used.
+
+The following options are recognized within B<Server> blocks:
+
=over 4
-=item B<Listen> I<Host> [I<Port>]
+=item B<SecurityLevel> B<Encrypt>|B<Sign>|B<None>
-=item B<Server> I<Host> [I<Port>]
+Set the security you require for network communication. When the security level
+has been set to B<Encrypt>, data sent over the network will be encrypted using
+I<AES-256>. The integrity of encrypted packets is ensured using I<SHA-1>. When
+set to B<Sign>, transmitted data is signed using the I<HMAC-SHA-256> message
+authentication code. When set to B<None>, data is sent without any security.
-The B<Server> statement sets the server to send datagrams B<to>. The statement
-may occur multiple times to send each datagram to multiple destinations.
+This feature is only available if the I<network> plugin was linked with
+I<libgcrypt>.
+
+=item B<Username> I<Username>
+
+Sets the username to transmit. This is used by the server to lookup the
+password. See B<AuthFile> below. All security levels except B<None> require
+this setting.
+
+This feature is only available if the I<network> plugin was linked with
+I<libgcrypt>.
+
+=item B<Password> I<Password>
+
+Sets a password (shared secret) for this socket. All security levels except
+B<None> require this setting.
+
+This feature is only available if the I<network> plugin was linked with
+I<libgcrypt>.
+
+=back
+
+=item B<E<lt>Listen> I<Host> [I<Port>]B<E<gt>>
The B<Listen> statement sets the interfaces to bind to. When multiple
statements are found the daemon will bind to multiple interfaces.
The argument I<Host> may be a hostname, an IPv4 address or an IPv6 address. If
the argument is a multicast address the daemon will join that multicast group.
+The optional second argument specifies a port number or a service name. If not
+given, the default, B<25826>, is used.
-If no B<Listen> statement is found the server tries join both, the default IPv6
-multicast group and the default IPv4 multicast group. If no B<Server> statement
-is found the client will try to send data to the IPv6 multicast group first. If
-that fails the client will try the IPv4 multicast group.
+The following options are recognized within C<E<lt>ListenE<gt>> blocks:
-The default IPv6 multicast group is C<ff18::efc0:4a42>. The default IPv4
-multicast group is C<239.192.74.66>.
+=over 4
+
+=item B<SecurityLevel> B<Encrypt>|B<Sign>|B<None>
+
+Set the security you require for network communication. When the security level
+has been set to B<Encrypt>, only encrypted data will be accepted. The integrity
+of encrypted packets is ensured using I<SHA-1>. When set to B<Sign>, only
+signed and encrypted data is accepted. When set to B<None>, all data will be
+accepted. If an B<AuthFile> option was given (see below), encrypted data is
+decrypted if possible.
+
+This feature is only available if the I<network> plugin was linked with
+I<libgcrypt>.
+
+=item B<AuthFile> I<Filename>
+
+Sets a file in which usernames are mapped to passwords. These passwords are
+used to verify signatures and to decrypt encrypted network packets. If
+B<SecurityLevel> is set to B<None>, this is optional. If given, signed data is
+verified and encrypted packets are decrypted. Otherwise, signed data is
+accepted without checking the signature and encrypted data cannot be decrypted.
+For the other security levels this option is mandatory.
+
+The file format is very simple: Each line consists of a username followed by a
+colon and any number of spaces followed by the password. To demonstrate, an
+example file could look like this:
-The optional I<Port> argument sets the port to use. It can either be given
-using a numeric port number or a service name. If the argument is omitted the
-default port B<25826> is assumed.
+ user0: foo
+ user1: bar
+
+Each time a packet is received, the modification time of the file is checked
+using L<stat(2)>. If the file has been changed, the contents is re-read. While
+the file is being read, it is locked using L<fcntl(2)>.
+
+=back
=item B<TimeToLive> I<1-255>
That means that multicast packets will be sent with a TTL of C<1> (one) on most
operating systems.
+=item B<MaxPacketSize> I<1024-65535>
+
+Set the maximum size for datagrams received over the network. Packets larger
+than this will be truncated.
+
=item B<Forward> I<true|false>
If set to I<true>, write packets that were received via the network plugin to
1800 seconds, but setting this to 86400 seconds (one day) will not do much harm
either.
+=item B<ReportStats> B<true>|B<false>
+
+The network plugin cannot only receive and send statistics, it can also create
+statistics about itself. Collected data included the number of received and
+sent octets and packets, the length of the receive queue and the number of
+values handled. When set to B<true>, the I<Network plugin> will make these
+statistics available. Defaults to B<false>.
+
=back
=head2 Plugin C<nginx>
=back
-=head2 Plugin C<ntpd>
+=head2 Plugin C<ntpd>
+
+=over 4
+
+=item B<Host> I<Hostname>
+
+Hostname of the host running B<ntpd>. Defaults to B<localhost>.
+
+=item B<Port> I<Port>
+
+UDP-Port to connect to. Defaults to B<123>.
+
+=item B<ReverseLookups> B<true>|B<false>
+
+Sets wether or not to perform reverse lookups on peers. Since the name or
+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.
+
+=back
+
+=head2 Plugin C<nut>
+
+=over 4
+
+=item B<UPS> I<upsname>B<@>I<hostname>[B<:>I<port>]
+
+Add a UPS to collect data from. The format is identical to the one accepted by
+L<upsc(8)>.
+
+=back
+
+=head2 Plugin C<olsrd>
+
+The I<olsrd> plugin connects to the TCP port opened by the I<txtinfo> plugin of
+the Optimized Link State Routing daemon and reads information about the current
+state of the meshed network.
+
+The following configuration options are understood:
=over 4
-=item B<Host> I<Hostname>
+=item B<Host> I<Host>
-Hostname of the host running B<ntpd>. Defaults to B<localhost>.
+Connect to I<Host>. Defaults to B<"localhost">.
=item B<Port> I<Port>
-UDP-Port to connect to. Defaults to B<123>.
+Specifies the port to connect to. This must be a string, even if you give the
+port as a number rather than a service name. Defaults to B<"2006">.
-=item B<ReverseLookups> B<true>|B<false>
+=item B<CollectLinks> B<No>|B<Summary>|B<Detail>
-Sets wether or not to perform reverse lookups on peers. Since the name or
-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.
+Specifies what information to collect about links, i.E<nbsp>e. direct
+connections of the daemon queried. If set to B<No>, no information is
+collected. If set to B<Summary>, the number of links and the average of all
+I<link quality> (LQ) and I<neighbor link quality> (NLQ) values is calculated.
+If set to B<Detail> LQ and NLQ are collected per link.
-=back
+Defaults to B<Detail>.
-=head2 Plugin C<nut>
+=item B<CollectRoutes> B<No>|B<Summary>|B<Detail>
-=over 4
+Specifies what information to collect about routes of the daemon queried. If
+set to B<No>, no information is collected. If set to B<Summary>, the number of
+routes and the average I<metric> and I<ETX> is calculated. If set to B<Detail>
+metric and ETX are collected per route.
-=item B<UPS> I<upsname>B<@>I<hostname>[B<:>I<port>]
+Defaults to B<Summary>.
-Add a UPS to collect data from. The format is identical to the one accepted by
-L<upsc(8)>.
+=item B<CollectTopology> B<No>|B<Summary>|B<Detail>
+
+Specifies what information to collect about the global topology. If set to
+B<No>, no information is collected. If set to B<Summary>, the number of links
+in the entire topology and the average I<link quality> (LQ) is calculated.
+If set to B<Detail> LQ and NLQ are collected for each link in the entire topology.
+
+Defaults to B<Summary>.
=back
B<Sensor> is inverted: All selected interfaces are ignored and all other
interfaces are collected.
+=item B<Interval> I<Seconds>
+
+Sets the interval in which all sensors should be read. If not specified, the
+global B<Interval> setting is used.
+
=back
B<EXPERIMENTAL!> The C<onewire> plugin is experimental, because it doesn't yet
Specifies the location of the status file.
+=item B<Compression> B<true>|B<false>
+
+Sets whether or not statistics about the compression used by OpenVPN should be
+collected. This information is only available in I<single> mode. Enabled by
+default.
+
=back
=head2 Plugin C<oracle>
=head2 Plugin C<ping>
+The I<Ping> plugin starts a new thread which sends ICMP "ping" packets to the
+configured hosts periodically and measures the network latency. Whenever the
+C<read> function of the plugin is called, it submits the average latency, the
+standard deviation and the drop rate for each host.
+
+Available configuration options:
+
=over 4
=item B<Host> I<IP-address>
Host to ping periodically. This option may be repeated several times to ping
multiple hosts.
+=item B<Interval> I<Seconds>
+
+Sets the interval in which to send ICMP echo packets to the configured hosts.
+This is B<not> the interval in which statistics are queries from the plugin but
+the interval in which the hosts are "pinged". Therefore, the setting here
+should be smaller than or equal to the global B<Interval> setting. Fractional
+times, such as "1.24" are allowed.
+
+Default: B<1.0>
+
+=item B<Timeout> I<Seconds>
+
+Time to wait for a response from the host to which an ICMP packet had been
+sent. If a reply was not received after I<Seconds> seconds, the host is assumed
+to be down or the packet to be dropped. This setting must be smaller than the
+B<Interval> setting above for the plugin to work correctly. Fractional
+arguments are accepted.
+
+Default: B<0.9>
+
=item B<TTL> I<0-255>
Sets the Time-To-Live of generated ICMP packets.
Select more detailed statistics of processes matching this name. The statistics
collected for these selected processes are size of the resident segment size
(RSS), user- and system-time used, number of processes and number of threads,
-and minor and major pagefaults.
+io data (where available) and minor and major pagefaults.
=item B<ProcessMatch> I<name> I<regex>
=back
+=head2 Plugin C<protocols>
+
+Collects a lot of information about various network protocols, such as I<IP>,
+I<TCP>, I<UDP>, etc.
+
+Available configuration options:
+
+=over 4
+
+=item B<Value> I<Selector>
+
+Selects whether or not to select a specific value. The string being matched is
+of the form "I<Protocol>:I<ValueName>", where I<Protocol> will be used as the
+plugin instance and I<ValueName> will be used as type instance. An example of
+the string being used would be C<Tcp:RetransSegs>.
+
+You can use regular expressions to match a large number of values with just one
+configuration option. To select all "extended" I<TCP> values, you could use the
+following statement:
+
+ Value "/^TcpExt:/"
+
+Whether only matched values are selected or all matched values are ignored
+depends on the B<IgnoreSelected>. By default, only matched values are selected.
+If no value is configured at all, all values will be selected.
+
+=item B<IgnoreSelected> B<true>|B<false>
+
+If set to B<true>, inverts the selection made by B<Value>, i.E<nbsp>e. all
+matching values will be ignored.
+
+=back
+
=head2 Plugin C<rrdcached>
-The C<rrdcached> plugin uses the RRDTool accelerator daemon, L<rrdcached(1)>,
+The C<rrdcached> plugin uses the RRDtool accelerator daemon, L<rrdcached(1)>,
to store values to RRD files in an efficient manner. The combination of the
C<rrdcached> B<plugin> and the C<rrdcached> B<daemon> is very similar to the
way the C<rrdtool> plugin works (see below). The added abstraction layer
You can use the settings B<StepSize>, B<HeartBeat>, B<RRARows>, and B<XFF> to
fine-tune your RRD-files. Please read L<rrdcreate(1)> if you encounter problems
-using these settings. If you don't want to dive into the depths of RRDTool, you
+using these settings. If you don't want to dive into the depths of RRDtool, you
can safely ignore these settings.
=over 4
"collection3" you'll end up with a responsive and fast system, up to date
graphs and basically a "backup" of your values every hour.
+=item B<RandomTimeout> I<Seconds>
+
+When set, the actual timeout for each value is chosen randomly between
+I<CacheTimeout>-I<RandomTimeout> and I<CacheTimeout>+I<RandomTimeout>. The
+intention is to avoid high load situations that appear when many values timeout
+at the same time. This is especially a problem shortly after the daemon starts,
+because all values were added to the internal cache at roughly the same time.
+
=back
=head2 Plugin C<sensors>
=back
+=head2 Plugin C<table>
+
+The C<table plugin> provides generic means to parse tabular data and dispatch
+user specified values. Values are selected based on column numbers. For
+example, this plugin may be used to get values from the Linux L<proc(5)>
+filesystem or CSV (comma separated values) files.
+
+ <Plugin table>
+ <Table "/proc/slabinfo">
+ Instance "slabinfo"
+ Separator " "
+ <Result>
+ Type gauge
+ InstancePrefix "active_objs"
+ InstancesFrom 0
+ ValuesFrom 1
+ </Result>
+ <Result>
+ Type gauge
+ InstancePrefix "objperslab"
+ InstancesFrom 0
+ ValuesFrom 4
+ </Result>
+ </Table>
+ </Plugin>
+
+The configuration consists of one or more B<Table> blocks, each of which
+configures one file to parse. Within each B<Table> block, there are one or
+more B<Result> blocks, which configure which data to select and how to
+interpret it.
+
+The following options are available inside a B<Table> block:
+
+=over 4
+
+=item B<Instance> I<instance>
+
+If specified, I<instance> is used as the plugin instance. So, in the above
+example, the plugin name C<table-slabinfo> would be used. If omitted, the
+filename of the table is used instead, with all special characters replaced
+with an underscore (C<_>).
+
+=item B<Separator> I<string>
+
+Any character of I<string> is interpreted as a delimiter between the different
+columns of the table. A sequence of two or more contiguous delimiters in the
+table is considered to be a single delimiter, i.E<nbsp>e. there cannot be any
+empty columns. The plugin uses the L<strtok_r(3)> function to parse the lines
+of a table - see its documentation for more details. This option is mandatory.
+
+A horizontal tab, newline and carriage return may be specified by C<\\t>,
+C<\\n> and C<\\r> respectively. Please note that the double backslashes are
+required because of collectd's config parsing.
+
+=back
+
+The following options are available inside a B<Result> block:
+
+=over 4
+
+=item B<Type> I<type>
+
+Sets the type used to dispatch the values to the daemon. Detailed information
+about types and their configuration can be found in L<types.db(5)>. This
+option is mandatory.
+
+=item B<InstancePrefix> I<prefix>
+
+If specified, prepend I<prefix> to the type instance. If omitted, only the
+B<InstancesFrom> option is considered for the type instance.
+
+=item B<InstancesFrom> I<column0> [I<column1> ...]
+
+If specified, the content of the given columns (identified by the column
+number starting at zero) will be used to create the type instance for each
+row. Multiple values (and the instance prefix) will be joined together with
+dashes (I<->) as separation character. If omitted, only the B<InstancePrefix>
+option is considered for the type instance.
+
+The plugin itself does not check whether or not all built instances are
+different. It’s your responsibility to assure that each is unique. This is
+especially true, if you do not specify B<InstancesFrom>: B<You> have to make
+sure that the table only contains one row.
+
+If neither B<InstancePrefix> nor B<InstancesFrom> is given, the type instance
+will be empty.
+
+=item B<ValuesFrom> I<column0> [I<column1> ...]
+
+Specifies the columns (identified by the column numbers starting at zero)
+whose content is used as the actual data for the data sets that are dispatched
+to the daemon. How many such columns you need is determined by the B<Type>
+setting above. If you specify too many or not enough columns, the plugin will
+complain about that and no data will be submitted to the daemon. The plugin
+uses L<strtoll(3)> and L<strtod(3)> to parse counter and gauge values
+respectively, so anything supported by those functions is supported by the
+plugin as well. This option is mandatory.
+
+=back
+
=head2 Plugin C<tail>
-The C<tail plugin> plugins follows logfiles, just like L<tail(1)> does, parses
+The C<tail plugin> follows logfiles, just like L<tail(1)> does, parses
each line and dispatches found values. What is matched can be configured by the
user using (extended) regular expressions, as described in L<regex(7)>.
=back
+=head2 Plugin C<teamspeak2>
+
+The C<teamspeak2 plugin> connects to the query port of a teamspeak2 server and
+polls interesting global and virtual server data. The plugin can query only one
+physical server but unlimited virtual servers. You can use the following
+options to configure it:
+
+=over 4
+
+=item B<Host> I<hostname/ip>
+
+The hostname or ip which identifies the physical server.
+Default: 127.0.0.1
+
+=item B<Port> I<port>
+
+The query port of the physical server. This needs to be a string.
+Default: "51234"
+
+=item B<Server> I<port>
+
+This option has to be added once for every virtual server the plugin should
+query. If you want to query the virtual server on port 8767 this is what the
+option would look like:
+
+ Server "8767"
+
+This option, although numeric, needs to be a string, i.E<nbsp>e. you B<must>
+use quotes around it! If no such statement is given only global information
+will be collected.
+
+=back
+
+=head2 Plugin C<ted>
+
+The I<TED> plugin connects to a device of "The Energy Detective", a device to
+measure power consumption. These devices are usually connected to a serial
+(RS232) or USB port. The plugin opens a configured device and tries to read the
+current energy readings. For more information on TED, visit
+L<http://www.theenergydetective.com/>.
+
+Available configuration options:
+
+=over 4
+
+=item B<Device> I<Path>
+
+Path to the device on which TED is connected. collectd will need read and write
+permissions on that file.
+
+Default: B</dev/ttyUSB0>
+
+=item B<Retries> I<Num>
+
+Apparently reading from TED is not that reliable. You can therefore configure a
+number of retries here. You only configure the I<retries> here, to if you
+specify zero, one reading will be performed (but no retries if that fails); if
+you specify three, a maximum of four readings are performed. Negative values
+are illegal.
+
+Default: B<0>
+
+=back
+
=head2 Plugin C<tcpconns>
The C<tcpconns plugin> counts the number of currently established TCP
=back
-=head2 Plugin C<teamspeak2>
-
-The C<teamspeak2 plugin> connects to the query port of a teamspeak2 server and
-polls interesting global and virtual server data. The plugin can query only one
-physical server but unlimited virtual servers. You can use the following
-options to configure it:
-
-=over 4
-
-=item B<Host> I<hostname/ip>
-
-The hostname or ip which identifies the physical server.
-Default: 127.0.0.1
-
-=item B<Port> I<port>
-
-The query port of the physical server. This needs to be a string.
-Default: "51234"
-
-=item B<Server> I<port>
-
-This option has to be added once for every virtual server the plugin should
-query. If you want to query the virtual server on port 8767 this is what the
-option would look like:
-
- Server "8767"
-
-This option, although numeric, needs to be a string, i.E<nbsp>e. you B<must>
-use quotes around it! If no such statement is given only global information
-will be collected.
-
-=back
-
=head2 Plugin C<thermal>
=over 4
=back
+=head2 Plugin C<tokyotyrant>
+
+The C<tokyotyrant plugin> connects to a TokyoTyrant server and collects a
+couple metrics: number of records, and database size on disk.
+
+=over 4
+
+=item B<Host> I<Hostname/IP>
+
+The hostname or ip which identifies the server.
+Default: B<127.0.0.1>
+
+=item B<Port> I<Service/Port>
+
+The query port of the server. This needs to be a string, even if the port is
+given in its numeric form.
+Default: B<1978>
+
+=back
+
=head2 Plugin C<unixsock>
=over 4
collect on-wire traffic you could, for example, use the logging facilities of
iptables to feed data for the guest IPs into the iptables plugin.
+=head2 Plugin C<write_http>
+
+This output plugin submits values to an http server by POST them using the
+PUTVAL plain-text protocol. Each destination you want to post data to needs to
+have one B<URL> block, within which the destination can be configured further,
+for example by specifying authentication data.
+
+Synopsis:
+
+ <Plugin "write_http">
+ <URL "http://example.com/post-collectd">
+ User "collectd"
+ Password "weCh3ik0"
+ </URL>
+ </Plugin>
+
+B<URL> blocks need one string argument which is used as the URL to which data
+is posted. The following options are understood within B<URL> blocks.
+
+=over 4
+
+=item B<User> I<Username>
+
+Optional user name needed for authentication.
+
+=item B<Password> I<Password>
+
+Optional password needed for authentication.
+
+=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|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>
+
+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<Format> B<Command>|B<JSON>
+
+Format of the output to generate. If set to B<Command>, will create output that
+is understood by the I<Exec> and I<UnixSock> plugins. When set to B<JSON>, will
+create output in the I<JavaScript Object Notation> (JSON).
+
+Defaults to B<Command>.
+
+=back
+
=head1 THRESHOLD CONFIGURATION
Starting with version C<4.3.0> collectd has support for B<monitoring>. By that
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>.
+
=back
=head1 FILTER CONFIGURATION
Satisfy "Any"
</Match>
+=item B<empty_counter>
+
+Matches all values with one or more data sources of type B<COUNTER> and where
+all counter values are zero. These counters usually I<never> increased since
+they started existing (and are therefore uninteresting), or got reset recently
+or overflowed and you had really, I<really> bad luck.
+
+Please keep in mind that ignoring such counters can result in confusing
+behavior: Counters which hardly ever increase will be zero for long periods of
+time. If the counter is reset for some reason (machine or service restarted,
+usually), the graph will be empty (NAN) for a long time. People may not
+understand why.
+
+=item B<hashed>
+
+Calculates a hash value of the host name and matches values according to that
+hash value. This makes it possible to divide all hosts into groups and match
+only values that are in a specific group. The intended use is in load
+balancing, where you want to handle only part of all data and leave the rest
+for other servers.
+
+The hashing function used tries to distribute the hosts evenly. First, it
+calculates a 32E<nbsp>bit hash value using the characters of the hostname:
+
+ hash_value = 0;
+ for (i = 0; host[i] != 0; i++)
+ hash_value = (hash_value * 251) + host[i];
+
+The constant 251 is a prime number which is supposed to make this hash value
+more random. The code then checks the group for this host according to the
+I<Total> and I<Match> arguments:
+
+ if ((hash_value % Total) == Match)
+ matches;
+ else
+ does not match;
+
+Please note that when you set I<Total> to two (i.E<nbsp>e. you have only two
+groups), then the least significant bit of the hash value will be the XOR of
+all least significant bits in the host name. One consequence is that when you
+have two hosts, "server0.example.com" and "server1.example.com", where the host
+name differs in one digit only and the digits differ by one, those hosts will
+never end up in the same group.
+
+Available options:
+
+=over 4
+
+=item B<Match> I<Match> I<Total>
+
+Divide the data into I<Total> groups and match all hosts in group I<Match> as
+described above. The groups are numbered from zero, i.E<nbsp>e. I<Match> must
+be smaller than I<Total>. I<Total> must be at least one, although only values
+greater than one really do make any sense.
+
+You can repeat this option to match multiple groups, for example:
+
+ Match 3 7
+ Match 5 7
+
+The above config will divide the data into seven groups and match groups three
+and five. One use would be to keep every value on two hosts so that if one
+fails the missing data can later be reconstructed from the second host.
+
+=back
+
+Example:
+
+ # Operate on the pre-cache chain, so that ignored values are not even in the
+ # global cache.
+ <Chain "PreCache">
+ <Rule>
+ <Match "hashed">
+ # Divide all received hosts in seven groups and accept all hosts in
+ # group three.
+ Match 3 7
+ </Match>
+ # If matched: Return and continue.
+ Target "return"
+ </Rule>
+ # If not matched: Return and stop.
+ Target "stop"
+ </Chain>
+
=back
=head2 Available targets