[Nagios-users] Fwd: NSCA MAX_PLUGINOUTPUT_LENGTH

[Andreas Ericsson]

Please don't crosspost to everywhere. It's about as polite as knocking 
on a door with the business end of a shotgun.

I've moved this to nagios-devel only for now, since that's where it belongs.

Ben O'Hara wrote:
> Ok,
>    So looking into this it appears that the limit is actually in
> nagios deinfined in includes/common.h as 348.
> 
> Obivously with more data being presented in the output, including
> perdata this is rather small.  Im having issues with getting perfdata
> for a "DISK" check that checks all filesystems so the output ends up
> being rather large.
> 
> Anybody see any reason not to raise this to a higher value? 2048? and
> also change it for NRPE?
> 

For nrpe and nsca, no. For Nagios it could mean service-checks are being 
garbled since the maximum POSIX-guaranteed atomic write-size is 512 
bytes. That must also include hostname and service-description, so 384 
is actually a calculated value for MAX_PLUGIN_OUTPUT_LENGTH.

> Does this effect other people? Should it be made as a generic change to nagios?
> 

It shouldn't be made a generic change to Nagios. The change that 
*should* be made is that Nagios should fork off commands and multiplex 
the output so as to get rid of the bottleneck that the FIFO introduces. 
I've done some fairly serious work on this but it sort of dropped 
between chairs as I got busy with other things (which is really a shame 
since it could easily provide a boost in nagios' performance by a factor 
of 40).

I'll get working on it again some rainy day or so.

-- 
Andreas Ericsson                   andreas.ericsson at op5.se
OP5 AB                             www.op5.se
Tel: +46 8-230225                  Fax: +46 8-230231


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