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From Daniel Ruggeri <>
Subject Re: [users@httpd] How to set up 2 or more machines running HTTPD instances to serve a same request ( in a load balanced fashion).
Date Fri, 06 Apr 2012 22:30:29 GMT
On 4/6/2012 10:34 AM, Pratapani wrote:
> Thanks for the reply.
> I have used the mod_proxy . Changed the httpd.conf to have 2 tomcat
> instances in cluster.
> <Proxy balancer://testcluster stickysession=JSESSIONID>
> BalancerMember ajp:// min=10 max=100 route=node1 loadfactor=1
> BalancerMember ajp:// min=20 max=200 route=node2 loadfactor=1
> </Proxy>
> Tomcat clustering works perfect. If Tomcat instance 1 ( node1 ) is shutdown
> , the request is serviced by instance 2 .
> I would like to have Apache HTTP Server also in cluster and avoid the single
> point of failure of Apache HTTP server i.e if one instance of Apache HTTP
> server is down, the application should still work.
> I did not find any configuration setting to make 2 Apache HTTP servers
> instances into a cluster.
> Appreciate your help.
> Durga Prasad

   What you are describing is outside the scope of httpd, unfortunately.
There are a few options - the two most popular are:
**Configure an HA VIP using OS-level clustering utilities* - this is the
windows managed integrated load balancer, or Linux-HA w/heartbeat. In
this configuration, you would bind both httpd instance to the same VIP
and allow the clustering utility to manage what node is live. With this
setup, your capacity at the web layer is limited to the capacity of a
single httpd server.
**An external load balancer* - this can be a hardware IP sprayer,
firewall, software service on another machine, etc. Anything operating
on layer 4 or up would do. In this sort of configuration you will bind
httpd to a distinct IP address bound to each machine in the load
balanced pair and let the upstream service manage the traffic. Capacity
in this configuration at the web layer scales linearly with each httpd
server. Beware, this option can be expensive.

Daniel Ruggeri

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