Nagios service latency

[Thomas Guyot-Sionnest]

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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...

Thomas
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