=head1 NAME

rrdtool tune - Modify some basic properties of a Round Robin Database

=head1 SYNOPSIS

B<rrdtool> B<tune> I<filename> 
S<[B<--heartbeat>|B<-h> I<ds-name>:I<heartbeat>]> 
S<[B<--minimum>|B<-i> I<ds-name>:I<min>]>
S<[B<--maximum>|B<-a> I<ds-name>:I<max>]>
S<[B<--data-source-type>|B<-d> I<ds-name>:I<DST>]>
S<[B<--data-source-rename>|B<-r> I<old-name>:I<new-name>]>

=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<RRD>).
All these tunable parameters together decide when data fed into an 
B<RRD> is to be regarded as invalid. Invalid data is entered into the 
database as *UNKNOWN*.

The main application of the B<tune> function is to relax the 
validation rules on an B<RRD>. This allows to fill a new B<RRD> with
data available in larger intervals than what you would normally want
to permit.

=over 8

=item I<filename>

The name of the B<RRD> you want to tune.

=item S<B<--heartbeat>|B<-h> I<ds-name>:I<heartbeat>>

modify the I<heartbeat> of a data source. By setting this to a high
value the rrd will accept things like one value per day ...

=item S<B<--minimum>|B<-i> I<ds-name>:I<min>>

alter the minimum value acceptable as input from the data source.
Setting I<min> to 'U' will disable this limit.

=item S<B<--maximum>|B<-a> I<ds-name>:I<max>>

alter the maximum value acceptable as input from the data source.
Setting I<max> to 'U' will disable this limit.

=item S<B<--data-source-type>|B<-d> I<ds-name>:I<DST>>

alter the type B<DST> of a data source.

=item S<[B<--data-source-rename>|B<-r> I<old-name>:I<new-name>]>

rename a data source

=back

=head1 EXAMPLE

C<rrdtool tune data.rrd -h in:100000 -h in:100000 -h in:100000>

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 <oetiker@ee.ethz.ch>

