multiple rrd files and graphing

[svjim]

I am a noob and going through the docs and how to's trying to get stuff setup to see if we can use Cacti for other purposes other than network monitoring. I am developer with some sysadmin skills.

I have a more theoretical question, say I wanted to know the temperature of each day of the week for an entire year. Would I need 7 different RRD files (one for each day of the week), each being able to contain say 2 data sources (high and low temp)? If that is the case, would I be able to display them all on one graph?

Any insight would be great.

[gandalf]

You will need a single rrd file, having two "data source items". Every 5 minutes, both items will be updated with current data. Using the appropriate graph template, you will be able to see both values in one graph, x-axis being the time axis. You may click the graph to see different default timespans, you may zoom in or choose predefined or self-defined timespans.
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R.

[svjim]

But how does the RRD know the difference between say Monday and Tuesday if I am putting in the high and low temps of those days? Wouldnt I have 14 data sources then (2 for each day of the week)?

[gandalf]

No. Each data source gets filled with data every 5 Minutes. Please read more about rrdtool to understand: http://oss.oetiker.ch/rrdtool
R.