=include name
-=head1 SYNOPSYS
+=head1 SYNOPSIS
-B<DEF>:I<vname>=I<RRD file>:I<ds name>:I<CF>[:step=I<step size>][:<time range>>]
+B<DEF:>I<E<lt>vnameE<gt>>=I<E<lt>rrdfileE<gt>>:I<E<lt>ds-nameE<gt>>:I<E<lt>CFE<gt>>[:step=I<E<lt>stepE<gt>>][:start=I<E<lt>timeE<gt>>][:end=I<E<lt>timeE<gt>>][:reduce=I<E<lt>B<CF>E<gt>>]
B<VDEF>:I<vname>=I<RPN expression>
These three instructions collect the data out of the B<RRD> files,
optionally altering it (think of a bytes to bits conversion) and
if desired you can define variables containing useful information
-such as maximum, mininimum etcetera. Two of the instructions use
+such as maximum, minimum etcetera. Two of the instructions use
a language called B<RPN> which is described in its own manual page.
=head1 DEF
-B<DEF>:I<vname>=I<RRD file>:I<ds name>:I<CF>[:step=I<step size>][:<time range>>]
+B<DEF:>I<E<lt>vnameE<gt>>=I<E<lt>rrdfileE<gt>>:I<E<lt>ds-nameE<gt>>:I<E<lt>CFE<gt>>[:step=I<E<lt>stepE<gt>>][:start=I<E<lt>timeE<gt>>][:end=I<E<lt>timeE<gt>>][:reduce=I<E<lt>B<CF>E<gt>>]
This command fetches data from an B<RRD> file. The virtual name
I<vname> can then be used throughout the rest of the script. By
default, an B<RRA> which contains the correct consolidated data
at an appropriate resolution will be chosen. The resolution can
-be overriden with the L<--step|rrdgraph/item_Time> option.
-The resolution can again be overriden by specifying the B<step size>.
-I<Not yet implemented:> [ The time span of this data
-is the same as for the graph by default, you can override this by
-specifying the B<time range>. ]
+be overridden with the L<--step|rrdgraph/item_Time> option.
+The resolution can again be overridden by specifying the B<step size>.
+The time span of this data is the same as for the graph by default,
+you can override this by specifying B<start and end>. Remember to
+escape colons in the time specification!
If the resolution of the data is higher than the resolution of off
graph, the data will be further consolidated. This may result in
image with width 400 and time span 400*1800 seconds (use appropriate
start and end times, such as C<--start end-8days8hours>).
+If consolidation needs to be done, the B<CF> of the B<RRA> specified in the
+B<DEF> itself will be used to reduce the data density. This behaviour can
+be changed using C<:reduce=I<E<lt>B<CF>E<gt>>>. This optional parameter
+specifies the B<CF> to use during the data reduction phase.
+
Example:
DEF:ds0=router.rrd:ds0:AVERAGE
DEF:ds0weekly=router.rrd:ds0:AVERAGE:step=7200
+ DEF:ds0weekly=router.rrd:ds0:AVERAGE:start=end-1h
+ DEF:ds0weekly=router.rrd:ds0:AVERAGE:start=11\:00:end=start+1h
=head1 VDEF
this I<vname> in another B<RPN> expression, you are effectively
inserting its value just as if you had put a number at that place.
The variable can also be used in the various graph and print
-elements. I<Not yet implemented:> [ Everywhere you can insert a
-number, you can also use the B<VDEF> (provided that it is set of course) ]
+elements.
Example: C<VDEF:avg=mydata,AVERAGE>