Nagios service latency

[Andreas Ericsson]

Thomas Guyot-Sionnest wrote:
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> On 03/11/07 05:03 AM, Andreas Ericsson wrote:
>> Thomas Guyot-Sionnest wrote:
>>> Something that can help as well is having the host check return as fast
>>> as possible.
>> If that's what you're after ...
> 
> It helped a lot reducing the check latency on my systems. It's running
> over 1000 checks/minute with near-0 latency (the latency climbs if
> there's a few hosts going down though, because the host check for down
> hosts is run more often and takes longer - I'll work on this when I
> upgrade to Nagios 3). The CPUs are used at about 50%.
> 
>>> On my servers I use check_icmp (faster than check_ping
>>> since it has native ICMP support), the check sends only one ping and
>>> timeout after one second (the minimum):
>>>
>>> # 'check_host-alive' command definition
>>> define command{
>>>   command_name check-host-alive
>>>   command_line $USER1$/check_icmp -H $HOSTADDRESS$ -w 300.00,80% -c
>>> 500.00,100% -p 1 -t 1
>>> }
>>>
>> Turn this into
>> # 'check_host-alive' command definition
>> define command{
>>     command_name check-host-alive
>>     command_line $USER1$/check_host -H $HOSTADDRESS$
>> }
> 
> This gives the same result for up hosts, but takes 20 times longer on
> unreachable hosts:
> 
> $ time ./check_icmp -H 1.1.1.1 -w 300.00,80% -c 500.00,100% -p 1 -t 1
> CRITICAL - 1.1.1.1: rta nan, lost 100%|rta=0.000ms;300.000;500.000;0;
> pl=100%;80;100;;
> 
> real    0m0.506s
> user    0m0.000s
> sys     0m0.004s
> $ time ./check_host -H 1.1.1.1
> CRITICAL - 1.1.1.1: rta nan, lost 100%|rta=0.000ms;1000.000;1000.000;0;
> pl=100%;100;100;;
> 
> real    0m10.006s
> user    0m0.000s
> sys     0m0.000s
> 
> So it's definitely not an option. I could further reduce the timeout by
> using lower thresholds but I wanted to stay on the safe side...
> 

You have check_attempts set to 1 for your hosts? Doesn't that generate an
awful amount of false positives?

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

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