Mrtg graph not updating
It will automatically interpolate the value of the data-source (DS) at the latest official time-slot (interval) and write this interpolated value to the log.
The original value you have supplied is stored as well and is also taken into account when interpolating the next log entry.
RRDs::graphv takes the same parameters as RRDs::graph but it returns a pointer to hash.
If RRDs::error does not return anything then the previous function has completed its task successfully.
You may log data at a 1 minute interval, but you might also be interested to know the development of the data over the last year.
You could do this by simply storing the data in 1 minute intervals for the whole year.
Consider upgrading to a standard conformant browser like Mozilla Firefox or Opera but also Apple's Safari or KDE's Konqueror for example.
If you see this text, this means that your browser does not support CSS2.
The function RRDs::error should be called to get the error status after each function call.
The RRD functions will not abort your program even when they cannot make sense out of the arguments you fed them.
For an introduction to the usage of RRDtool make sure you consult the rrdtutorial.
While the man pages talk of command line switches you have to set in order to make RRDtool work it is important to note that RRDtool can be remotely controlled through a set of pipes.