rrd_hwreapply - Re-apply Holt-Winters prediction parameters to RRD data


rrd_hwreapply in.rrd out.rrd [--force] [--start=start] [--delta=scale-value] [--deltapos=scale-value] [--deltaneg=scale-value] [--failure-threshold=failure-threshold] [--window-length=window-length] [--alpha=adaption-parameter] [--beta=adaption-parameter] [--gamma=adaption-parameter] [--gamma-deviation=adaption-parameter] [--rralen=rows] [--season=rows] [--defaults]


The prorgam takes the input RRD, and copies all data to the output RRD, with new Holt-Winters prediction parameters applied. If the input file is not Holt-Winters enabled, all parameters must be specified, or use the --defaults option.

The resulting RRD will not contain exactly the same data as the source file. It is a result of numerous transformations during the data fetching and storing. However, the tests have shown quite good results: for a counter with average values of order of 1e+06, the resulting data relative difference is of order of 1e-10. For a counter with average values at the level of 1e+03, the precision is approximately 1e-08.


Forces the output file to be overwritten. Otherwise the program terminates if the output file already presents.

Specifies the earliest date to copy the data for. If not specified, the earliest available data with one-step (no consolidation) AVERAGE RRAs will be taken.

--delta=scale-value, --deltapos=scale-value, --deltaneg=scale-value, --failure-threshold=failure-threshold, --window-length=window-length, --alpha=adaption-parameter, --beta=adaption-parameter, --gamma=adaption-parameter, --gamma-deviation=adaption-parameter
Set the Holt-Winters algorithm parameters. See rrdtune(1) and the article of Jake Brutlag on Aberrant Behavior Detection.

Set the length of HWPREDICT RRA. Default is 4032 (2 weeks of 5-minute samples).

Set the length of SEASONAL RRA. Default is 288 (1 day of 5-minute samples).

Use the default values for all Holt-Winters parameters. Individual parameters may be overwritten by the above options. The default values are:
 delta = 2
 alpha = 0.1
 beta  = 0.0035
 gamma = 0.1
 window_length = 9
 failure_threshold = 6
 hw_rra_length = 4032
 seasonal_period = 288


This program requires RRDtool version 1.1.x (currently available as development snapshot only), Perl version 5.8.2 (version 5.8.0 is known to have bugs which break this utility).


RRDman is a set of utilities that manipulate the RRDtool database files.


Stanislav Sinyagin <>