[mrtg] Re: Lockfiles and program flow

Volk,Gregory B greg.volk at edwardjones.com
Mon Oct 10 14:23:08 MEST 2005

> Mrtg 2.10.15 running on Sun V440 on Solaris 8 using rrdtool 1.0.50
> 15 instances of mrtg are running from cron once a minute at a 
> 15 minute interval. So there is an instance of mrtg starting every 
> minute. 
> Total number of targets almost 60,000
> **Serious** I/O problems, which we are working on to resolve by 
> adding hardware, but in the meantime management wants us to try to 
> "make it work" on the 2 striped disks we have.

Wow, I thought I was the only person running MRTG on a big, 
overpriced, slow Sun box these days. ;) I poll 25,060 two 
variable targets on a five minute interval. I do this on top 
of Solaris 8 on V440 hardware (4 procs, 8 gigs) but I store all 
the RRD files on EMC dasd. Prior to moving the WorkDir to the 
EMC my system was falling over because it was so always really 
I/O bound. I know EMC is a bitter, expensive, pill to swallow, 
but without it, the processing horsepower of a V440 pretty 
much goes to waste (at least in my case it does).

Your 15 config files must be gargantuan! I spread out my 25,000
targets among 80 MRTG invocations running in daemon mode.

If you can't swing the dollars for an EMC frame, you might want
to look into a RAM filesystem - if the V440 can accomodate 
enough RAM that would allow you to put your WorkDir on a RAM 
filesystem that would get around the disk IO issues you have,
but of course then you have volatility issues in the event of
a crash. :(

> Two lockfiles are created, $lockfile and $templock. $templock 
> disappears
> early on--haven't figure out when exactly, but by the time 
> the SNMP metrics
> are being collected it seems to be gone.  Is this by design? $lockfile
> disappears when "Remove lock files" shows up in log (with 
> --debug=base) --
> once the entire run has completed.
> How can I tell if my runs are completing in within 15 
> minutes? What is going
> on here?

I'm not sure what $templock is, but you might want to turn
on logging via the...
--logging mrtg.log
...command line directive, but I don't know if that command 
option works outside of daemon mode. I'm thinking that 
debugging the base set will not tell you whether or not
you're meeting the time limits.

If --logging doesn't tell you anything in cron mode, try 
running one of your 15 config files in Daemon mode by putting 
RunAsDaemon:Yes at the top, and then turn on logging via the 
command line. I am certain that an 'interval exceeded' message
will appear in the log file if the poll cycle takes too 
long - I've seen it happen in my own stuff in the past.

Good luck.

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