Cacti uses RRDtool to store and graph its performance data. RRD files store data in a fixed size file using a First In, First Out (FIFO) methodology and in order to aggregate data, different Round Robin Archives (RRA) are defined within a single RRD file. These RRAs usually consist of daily, weekly, monthly and yearly archives but can be freely defined.
The Round Robin database tool
The RRD file architecture
The principal of an RRD file is shown in the next figure. We have defined three Round Robin Archives, one storing 5 minute polling data, one RRA storing 20 minutes (4 * 5 minute polling data) aggregated data and another one storing the hourly (12 * 5 minute polling data) aggregated data.
In this example, the data...
