[rrd-users] NEWBIE: Is RRDTools suitable for procession non-continuous data?

[u7l11ey at mail.lrz-muenchen.de]

Hi RRDTools community,

I am a complete newbie with RRDTools and am wondering if it is suitable for
the project I am planning:

I want to log and graphically display data from my solar heating system.
The system controller sends information about its input and output ports
(e.g. temperature from solar circuit or power level of a pump) over a
serial line in a kind of XML format, e.g.
<OBJVAL>P2=84</OBJVAL><OBJVAL>PZ=27</OBJVAL><OBJVAL>VF1=489</OBJVAL>
<OBJVAL>AF=58</OBJVAL> and so on, in a continuous data stream that has
a new record appended for a parameter only when its value changes. These
changes happen at very irregular intervals. The value for a temperature
sensor may change every second, while the status of a valve may stay the
same for days.

What I've learned so far about RRDTools that it expects values ("PDP") for
its parameters ("DS") at regular intervals, otherwise it will store
"UNKNOWN" for this parameter. This is obviously not what I need. I thought
about using a small database (MySQL?) to cache the current value for each
parameter, but since the whole system has to run on a NSLU2 with uNSLUng
(or maybe Debian), I have to keep it as simple and processor-saving as
possible.

So can I use RRDTools for my purpose, or should I go on and look elsewhere?

Regards, Richard