If  you know MRTG, you can think of RRDtool as a reimplemen-
tation of MRTGs graphing and  logging  features.  Magnitudes
faster and more flexible than you ever thought possible

RRD is the Acronym for Round Robin Database. RRD is a system
to store and display time-series data  (i.e.  network  band-
width,  machine-room  temperature,  server load average). It
stores the data in a very compact way that will  not  expand
over  time,  and it presents useful graphs by processing the
data to enforce a certain  data  density.  It  can  be  used
either  via  simple  wrapper scripts (from shell or Perl) or
via frontends that poll network devices and put  a  friendly
user interface on it

WWW: http://ee-staff.ethz.ch/~oetiker/webtools/rrdtool/
