[f-nsp] Response-time balancing

[Mischa Peters]

Hi Vlad,

The weight that you can add to a real server only applies to the  
predictor weighted.
When you apply the predictor least connections, you can not configure  
anything at real server level.
The url that you are using only applies to health checks. If you want  
to tie this is with the load balancing mechanism you need to create an  
http match list.

Something like:

http match-list hc
   default down
   up simple UP
   down simple DOWN

If you then tie this together at the real server like:

port http keepalive
port http url "GET /cgi-bin/la.cgi"
port http content-match hc

If you have your script present a DOWN when it's over it's limit and  
an UP when it's not you will get what you want from the script.
When the script presents DOWN it leave existing connections alone but  
this server will not be used for the next incoming connection.

Hope this helps.

Mischa

> Hello,
>
> we are using ServerIron XL to load-balance http traffic configured
> with DSR. Real servers hardware is pretty different, so I thought
> using response-time predictor logic is adequate. I've written a simple
> script that checks real server load average and delays it response
> proportionally to that LA. That script is specified like this for each
> real server:
>
> port http keepalive
> port http url "GET /cgi-bin/la.cgi"
>
>
> what I've being observing is ServerIron distributes requests pretty
> evenly according to each real server processing capacity. However
> every once in a while, all of the sudden SI would send tons of new
> connections to a single real server, overloading it for few moments.
>
> To fight that I tried to setup balancing by "Least connection and
> server response time weights", but documentation is not quite clear.
>
> I assume that each real server should be given "weight X Y"
> configuration option, where X represents connections weight, Y - its
> response time weight. It's not clear what "predictor" should be set to
> account for both values - to weighted or least-connection or
> response-time... I tried every single with no luck - it either
> balances on connections or response time but not combination.
>
> Did anyone has a similar problem or ideas on optimal load balancing
> when real servers has very uneven processing capacity.
>
> --
> Vlad
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