=head1 NAME

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

=for html <div align="right"><a href="rrdtune.pdf">PDF</a> version.</div>

=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>]>
S<[B<--deltapos> I<scale-value>]>
S<[B<--deltaneg> I<scale value>]>
S<[B<--failure-threshold> I<failure-threshold>]>
S<[B<--window-length> I<window-length>]>
S<[B<--alpha> I<adaption-parameter>]>
S<[B<--beta> I<adaption-parameter>]>
S<[B<--gamma> I<adaption-parameter>]>

=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*.

One 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. Be very careful with tune operations for COMPUTE data sources.
Setting the I<min>, I<max>, and  I<heartbeat> for a COMPUTE data source
without changing the data source type to a non-COMPUTE B<DST> WILL corrupt
the data source header in the B<RRD>.

A second application of the B<tune> function is to set or alter parameters
used by the specialized function B<RRAs> for aberrant behavior detection.

=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

=item S<B<--deltapos> I<scale-value>>

Alter the deviation scaling factor for the upper bound of the confidence band
used internally to calculate violations for the FAILURES B<RRA>. The default
value is 2. Note that this parameter is not related to graphing confidence
bounds, that scale factor must be specified as a CDEF argument to generate 
a graph with confidence bounds. It need not agree with the value used internally 
by the FAILURES B<RRA> (although common sense dictates it should).

=item S<B<--deltaneg> I<scale-value>>

Alter the deviation scaling factor for the lower bound of the confidence band
used internally to calculate violations for the FAILURES B<RRA>. The default
value is 2. As with B<--deltapos>, this argument is unrelated to the scale
factor chosen when graphing confidence bounds.

=item S<B<--failure-threshold> I<failure-threshold>>

Alter the number of confidence bound violations that constitute a failure for
purposes of the FAILURES B<RRA>. This must be an integer less than or equal to
the window length of the FAILURES B<RRA>. This restriction is not verified by
the tune option, so one can reset failure-threshold and window-length 
simultaneously. Setting this option will reset the count of violations to 0.

=item S<B<--window-length> I<window-length>>

Alter the number of time points in the temporal window for determining failures.
This must be an integer greater than or equal to the window length of the
FAILURES B<RRA> and less than or equal to 28. Setting this option will reset the
count of violations to 0.

=item S<B<--alpha> I<adaption-parameter>>

Alter the intercept adaptation parameter for the Holt-Winters forecasting algorithm.
Must be between 0 and 1.

=item S<B<--beta> I<adaption-parameter>>

Alter the intercept adaptation parameter for the Holt-Winters forecasting algorithm.
Must be between 0 and 1.

=item S<B<--gamma> I<adaption-parameter>>

Alter the seasonal coefficient and deviation adaptation parameters the SEASONAL and
DEVSEAONAL B<RRAs>. Must be between 0 and 1.

=back

=head1 EXAMPLE 1

C<rrdtool tune data.rrd -h in:100000 -h out:100000 -h through: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 EXAMPLE 2

C<rrdtool tune monitor.rrd --window-length 5 --failure-threshold 3>

If the FAILURES B<RRA> is implicitly created, the default window-length is 9 and 
the default failure-thresold is 7. This command now defines a failure as 3 or more
violations in a temporal window of 5 time points.

=head1 AUTHOR

Tobias Oetiker <oetiker@ee.ethz.ch>