Mailing List Archive

frank bretschneider wrote:
> hi ..
>
> i am using mod_backhand to load balance a server cluster.
> somehow it does not really balance the load of the servers.
>
> my rules are ...
>
> <Directory /www/htdocs>
> Backhand removeSelf
> Backhand byAge
> Backhand byLoad
> Backhand byRandom

Here you tell it to randomly assign traffic. So it will. I would suggest
taking the byRandmon out. With 4 servers and a front end, I would try
something like:

Backhand removeSelf
Backhand byAge
Backhand byBusyChildren

Load is a slowly adjusting metric and not very well suited to web traffic. As
a thousand requests could come to a single machine over a few second period
and the load will not update to reflect that workload for several more seconds
and not fully for a minute.

BusyChildren is designed to be a "point in time" run queue length estimator
based on the number of occupied Apache children. It isn't perfect, but tests
show that it works very well.

> # Backhand byBusyChildren
> </Directory>
>
> i am using one apache front server and 4 apache backhand servers.
> three backhand servers have almost the same hardware. the 4th server
> has the slowest hardware. this server gets a real high load a lot of
> times. so the rule "by Load" does not seam to work.
>
> as a work around i would like to reduce the max amount of clients on
> this slow machine. does anybody know if the frontserver will recognize
> if the max. amount of clients is reached on a backhanded server and
> will not forward any requests to this server till there is a new client
> available.
>
> thx.
>

--
Theo Schlossnagle
Principal Consultant
OmniTI Computer Consulting, Inc. -- http://www.omniti.com/
Phone: +1 410 872 4910 x201 Fax: +1 410 872 4911
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