[smokeping-users] Re: Forks & monitoring data reliability

[Niko Tyni]

On Mon, Jun 06, 2005 at 10:30:29AM +0800, Joe Shen wrote:
 
> I use smokeping to monitor our DNS server service
> quality. I set up smokeping to query 4 domain names
> every 5 minutes, in which 20 queries are executed
> consequently. The configuration file looks alike:
> 
> 
> *** Database ***
> 
> step     = 300
> pings    = 20
> 
> + DNS 
> 
> binary = /usr/local/bin/dig
> forks = 40
> timeout = 10
 
> I found that the result of monitoring result degrade
> apparentaly ( packet loss shown on the graph) after I
> add four testing items ( target with host option). The
> total number of target with host option is  45.

Hi,

I'm afraid I don't quite understand. Maybe you're mixing up the 'host'
variable (the DNS server to be probed) and the 'lookup' variable (the
DNS name to be looked up)? If you are testing just a single server and
4 domain names, there should be just 4 targets (each having the same
'host' value, but a different 'lookup' value). Where do the numbers
40 or 45 come from?

The same query is done 20 (or whatever the 'pings' value is) times in a
row for each target to get a decent sample of the average response
time. This is not a bug, it's a feature :)

> 1. If I set forks=80, would somkeping probe each host
> with seperate process ? Could this way remove
> sideeffect of sequent probing?

If you have more 'forks' than targets, each target is probed at the
same time in its own subprocess. 40 or 80 still sounds quite high,
though.  I'm not sure what you mean by 'sequent probing' - maybe the
'20 pings' stuff mentioned above?

> 2. How to set up timeout value to reach most reliable
> probing data set?

It should be the number of seconds without response after which you
decide that the server is down and is not going to respond at all.
10 might be a bit high here, but YMMV.

Hope this helps. If you still have problems, please try to explain them
more (like what do you mean by the results degrading? with regard to
what?). Please mention your Smokeping version as well and send your
full config file, or at least *both* the Probes and Targets part.

Cheers,
-- 
Niko Tyni	ntyni at iki.fi

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