Hello,<div><br></div><div>I've been experimenting with using the holt-winters prediction in rrdtool and figured it would be really nice to have the option for collectd to create RRDs with the HWPREDICT RRAs. The attached patch adds three configuration options, HWPredictSeasonTimespan (the seasonality of your data in seconds -- set this to something non-zero to enable), HWPredictAlpha (determines the rate of intercept adaptation for holt-winters, defaults to 0.01. Higher adapts faster.) and HWPredictBeta (determines the rate of slope adaptation, defaults to 0.00035, higher adapts faster).</div>
<div><br></div><div>Seems to work properly in my testing, resulting in RRDs with all the necessary RRAs. I'm using the simple method of creating these, passing only the HWPREDICT definition and allowing RRDtool to automatically create the appropriate sized record-keeping RRAs. </div>
<div><br></div><div>One word of caution: depending on the step-size chosen for your RRDs, this can result in much larger RRDs. Holt-Winters works on the raw data points, not aggregated data points, which can produce some big RRAs. If your step size is 10 seconds and your data is periodic over a week, this will result in RRAs with 60480 rows. Practically, it means that the RRD filesize goes from 58KB to 2.4MB. I suppose that's the price to be paid if you need to prediction functionality, though.</div>
<div><br></div><div>Anyway, hopefully someone else finds this useful!</div><div><br></div><div>--Shaun</div>