Graph Any Data with Cacti!

The second field is to choose a color for the graph. Irritatingly, the drop-down menu shows only HEX codes for colors, but after you select one, it displays the color for you. Houston is generally hot, so it seemed appropriate for it to be red. Next is opacity, and I chose 100%. The "Graph Item Type" does not default to "AREA", so be sure to select that for a traditional graph that looks like a rolling hill of data. It's safe to leave "Consolidation Function" to AVERAGE, and everything else the default. I did add "Houston Temp" to the Text Format field, so it shows which color is which Data Source on my graph. Once you're happy with the data, click Create. Do the same thing with your second Data Source. You'll notice in mine (Figure 18) that I chose blue for Petoskey, and instead of AREA, I chose LINE1. It's a different type of graph, so that instead of filling the page, it will draw a line with the temperature. I did that so Houston would fill the background, and Petoskey would draw a line over the top of it, so you can see both. Figure 19 shows the preview of what the graph will look like. Be sure to click Save at the bottom!

Figure 18. Blue seemed appropriate for Petoskey.

Figure 19. Looks like the graph is configured. (Don't forget to click Save.)

That's It!

The only thing left to do is wait. Every five minutes, there should be a data point added, and the graphs will update with a graphical representation of that data. Cacti allows you to export the graphs to a local path (like /var/www/html) or to a remote FTP server. If you don't have it export the graphs, you'll have to log in to see them. I won't go through the process for exporting the graphs, but click on the "settings" link on the left column, and then the "Graph Export" tab across the top. The setup is fairly self-explanatory. To see the graphs you've just created, wait 10–15 minutes, then follow the arrows as shown in Figure 20 to find the graphs. You should see your new graphs starting to populate themselves with data!

Figure 20. These are frustrating to find; hopefully the arrows help you.

Cacti has lots of other features, and it allows you to customize your graphs with min/max values displayed on the graphic, along with different types of graphs, data sources and so on. Once you become familiar with using it, Cacti is a very nice tool for automating the graphing process. I hope you have as much fun with it as I did!

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Shawn Powers is a Linux Journal Associate Editor. You might find him on IRC, Twitter, or training IT pros at CBT Nuggets.