[rrd-users] Dilemma in using COUNTER to monitor a system that could crash and reset its parameters

[David Lee]

Hi all rrdTool users,
 

I am using rrdTool to monitor a system that resets all its parameters to
0 whenever it crashes. The system has high traffic volume so the chance
of variable overflow is high. 

 

I am using the data type COUNTER to track the system parameters, but I
am running into this problem:

When the system restarts after a crash, all the new parameter readings
will be smaller than the previous ones in the rrdtool database. So
rrdtool will be tricked to think that a COUNTER overflow had occurred.
The new values will be incorrectly displayed in the graph as many
magnitudes greater.

 

How do I get around this problem? Do I have to:

1)       create new rrd database whenever the system crashes so the data
in the DB remains fresh? (But I don't want to loose all the historic
data.)

2)       or use the data Type DERIVE to take into account for a negative
rate (i.e. a reading drop), but DERIVE (and ABSOLUTE for that matter)
does not have overflow protection that I desire.

 

What would be the best approach to solve this problem?

 

Much thanks in advance.

 

Dave

 

 


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