This patch introduces a feature whereby rrdcached will disallow updates

[rrdtool.git] / doc / rrdupdate.pod

diff --git a/doc/rrdupdate.pod b/doc/rrdupdate.pod
index cc0b452..c285ee3 100644 (file)
--- a/doc/rrdupdate.pod
+++ b/doc/rrdupdate.pod
@@ -6,6 +6,7 @@ rrdupdate - Store a new set of values into the RRD
 
 B<rrdtool> {B<update> | B<updatev>} I<filename>
 S<[B<--template>|B<-t> I<ds-name>[B<:>I<ds-name>]...]>
+S<[B<--daemon> I<address>]>
 S<B<N>|I<timestamp>B<:>I<value>[B<:>I<value>...]>
 S<I<at-timestamp>B<@>I<value>[B<:>I<value>...]>
 S<[I<timestamp>B<:>I<value>[B<:>I<value>...] ...]>
@@ -29,6 +30,9 @@ RRA (consolidation function and PDPs per CDP), and data source (name).
 Note that depending on the arguments of the current and previous call to
 update, the list may have no entries or a large number of entries.
 
+Since B<updatev> requires direct disk access, the B<--daemon> option cannot be
+used with this command.
+
 =item I<filename>
 
 The name of the B<RRD> you want to update.
@@ -56,6 +60,15 @@ function. If this is done accidentally (and this can only be done
 using the template switch), B<RRDtool> will ignore the value specified
 for the COMPUTE B<DST>.
 
+=item B<--daemon> I<address>
+
+If given, B<RRDTool> will try to connect to the caching daemon L<rrdcached>
+at I<address> and will fail if the connection cannot be established. If the
+connection is successfully established the values will be sent to the daemon
+instead of accessing the files directly.
+
+For a list of accepted formats, see the B<-l> option in the L<rrdcached> manual.
+
 =item B<N>|I<timestamp>B<:>I<value>[B<:>I<value>...]
 
 The data used for updating the RRD was acquired at a certain
@@ -82,20 +95,65 @@ separator.
 
 =back
 
-=head1 EXAMPLE
+=head1 ENVIRONMENT VARIABLES
+
+The following environment variables may be used to change the behavior of
+C<rrdtoolE<nbsp>update>:
+
+=over
+
+=item B<RRDCACHED_ADDRESS>
+
+If this environment variable is set it will have the same effect as specifying
+the C<--daemon> option on the command line. If both are present, the command
+line argument takes precedence.
+
+=back
+
+=head1 EXAMPLES
+
+=over
+
+=item *
 
 C<rrdtool update demo1.rrd N:3.44:3.15:U:23>
 
 Update the database file demo1.rrd with 3 known and one I<*UNKNOWN*>
 value. Use the current time as the update time.
 
+=item *
+
 C<rrdtool update demo2.rrd 887457267:U 887457521:22 887457903:2.7>
 
 Update the database file demo2.rrd which expects data from a single
 data-source, three times. First with an I<*UNKNOWN*> value then with two
 regular readings. The update interval seems to be around 300 seconds.
 
-=head1 AUTHOR
+=item *
+
+C<rrdtool update --cache /var/lib/rrd/demo3.rrd N:42>
+
+Update the file C</var/lib/rrd/demo3.rrd> with a single data source, using the
+current time. If the caching daemon cannot be reached, do B<not> fall back to
+direct file access.
+
+=item *
+
+C<rrdtool update --daemon unix:/tmp/rrdd.sock demo4.rrd N:23>
+
+Use the UNIX domain socket C</tmp/rrdd.sock> to contact the caching daemon. If
+the caching daemon is not available, update the file C<demo4.rrd> directly.
+B<WARNING:> Since a relative path is specified, the following disturbing effect
+may occur: If the daemon is available, the file relative to the working
+directory B<of the daemon> is used. If the daemon is not available, the file
+relative to the current working directory of the invoking process is used.
+B<This may update two different files depending on whether the daemon could be
+reached or not.> Don't do relative paths, kids!
+
+=back
+
+=head1 AUTHORS
 
-Tobias Oetiker <tobi@oetiker.ch>
+Tobias Oetiker <tobi@oetiker.ch>,
+Florian Forster <octoE<nbsp>atE<nbsp>verplant.org>