I am attempting to use rrdtool to capture and display weather data. I have run into a few issues where I could use some clarification and help in using rrdtool better.
I want to keep some historical data. However it appears the graphing function will consolidate data to fit on a particular graph. It doesn't make sense to keep data that will never be displayed. How do I determine reasonable disk space usage (number of samples) based on my graphing requirements (last month, last year, etc.)? Most of the data types are gauges. However a few data types have different properties. Rain is a counter in that it increases. However it is nice to see the sum over a certain period of time. The consolidation functions all appear to interfere with the summation over time. How can I get the total rainfall out of rrdtool? Can I use a LAST RRA? How would I get total rainfall for the last year, month, day (assuming I keep that much data)? Wind speed could be a gauge or a counter. Total wind isn't very interesting so it doesn't have the same issue as rain. However it is nice to see maximums (gusting). It looks like the MAXIMUM consolidation function would keep this information. If the wind is a counter (wind rate), can I still get the absolute number (kph or mph)? Wind direction seems to be the most challenging for rrdtool to accommodate. Wind direction can be broken down into 16 compass points. It would be nice to be able to show the maximum wind gust came from a certain direction. This would require a way to extract the data for a given time. It looks like rrdtool fetch will do this, wont it? The difficult part for wind direction is the consolidation function. Averaging or max/min won't work. Looks like I need a "most common value" (mode) consolidation function? Any other ideas on how to handle this? On the display side, I wrote a perl cgi script that fetched all the data and attempts to work around some of the issues above. However I couldn't avoid all of them. Any feedback would be appreciated. Thanks, Greg -- Unsubscribe mailto:[EMAIL PROTECTED] Help mailto:[EMAIL PROTECTED] Archive http://www.ee.ethz.ch/~slist/rrd-users WebAdmin http://www.ee.ethz.ch/~slist/lsg2.cgi
