[hobbit] rrd graphing questions - how to ignore items?

[Stef Coene]

On Friday 12 December 2008, Brand, Thomas R. wrote:
> Hi all,
>
>   I have set up a 'mysql' status check as an external script:
> ~hobbit/client/ext/bb-mysqlstatus.sh
>
> It sends up several informational lines (see below), only some of which
> I want to graph.
>
> I only want to graph "Threads", "Slow queries", and "Open Tables".
>
> If I only send up the 3 lines I want to graph, everything works as
> desired.  However, if I add more lines, the graph stops working.  I'm
> guessing that I need to add something somewhere to tell RRD to ignore
> the lines I don't want to graph... but where/how?
If an rrd is created, the number of counters is fixed.  So, if you initally 
used 3 counters, the rrd is for these 3 counters.  If you later send on a 
status message with 5 counters, the rrd will not be updated because it does 
not match.
I have a script to add a DS to an existing rrd.  An other option is throw away 
the existing rrd.

So, never change the number of counters in a rrd.  Or the name of the 
counters.


Stef