=head1 NAME
rrdtune - Modify some basic properties of a Round Robin Database
=for html
=head1 SYNOPSIS
B B I
S<[B<--heartbeat>|B<-h> I:I]>
S<[B<--minimum>|B<-i> I:I]>
S<[B<--maximum>|B<-a> I:I]>
S<[B<--data-source-type>|B<-d> I:I]>
S<[B<--data-source-rename>|B<-r> I:I]>
=head1 DESCRIPTION
The tune option allows you to alter some of the basic configuration
values stored in the header area of a Round Robin Database (B).
All these tunable parameters together decide when data fed into an
B is to be regarded as invalid. Invalid data is entered into the
database as *UNKNOWN*.
The main application of the B function is to relax the
validation rules on an B. This allows to fill a new B with
data available in larger intervals than what you would normally want
to permit.
=over 8
=item I
The name of the B you want to tune.
=item S|B<-h> I:I>
modify the I of a data source. By setting this to a high
value the RRD will accept things like one value per day ...
=item S|B<-i> I:I>
alter the minimum value acceptable as input from the data source.
Setting I to 'U' will disable this limit.
=item S|B<-a> I:I>
alter the maximum value acceptable as input from the data source.
Setting I to 'U' will disable this limit.
=item S|B<-d> I:I>
alter the type B of a data source.
=item S<[B<--data-source-rename>|B<-r> I:I]>
rename a data source
=back
=head1 EXAMPLE
C
Set the minimum required heartbeat for data sources 'in', 'out'
and 'through' to 10000 seconds which is a little over one day in data.rrd.
This would allow to feed old data from MRTG-2.0 right into
RRDTool without generating *UNKNOWN* entries.
=head1 AUTHOR
Tobias Oetiker