N2RRD (Nagios to Round Robin Database) is a Nagios add-on tool, which stores performance data generated by Nagios plugins into a Round-Robin-Database (see RRDtool). The package also includes the display tool rrd2graph to view data stored in an RRD database.Optionally data stored by N2RRD can also be viewed by any RRD database graph frontend e.g. Cacti, Drraw, etc.n2rrd is free software, licensed under the GNU General Public License Version 2 as published by the Free Software Foundation.