First install the following gems:
#su
#gem install mongrel
#gem install mongrel_cluster
#cd project_name
#mongrel_rails cluster::configure -e production -p 3000 -N 3 -c /home/siwan/project_name -a 127.0.0.1 —-prefix /project_name
# mongrel_rails cluster::start

You are able to start your applicaton at http://127.0.0.1:3000, http://127.0.0.1:3001 and http://127.0.0.1:3002

for all the cluster
# mongrel_rails cluster::stop

Advanced prepairation for production realeaze
$ mkdir /etc/mongrel_cluster

#vim /etc/mongrel_cluster/project_name.yml
copy and paste following text;
user: project_name
cwd: //home/siwan/project_name
log_file: /home/siwan/project_name/mongrel.log
port: “3000″
environment: production
group: dev
address: localhost
pid_file: /home/siwan/project_name/tmp/pids/mongrel.pid
servers: 3

or you can run the following command

or copy and paste the content from config/mongrel_cluster.yml file to /etc/mongrel_cluster/project_name.yml

# ln -s /home/siwan/project_name/config/mongrel_cluster.yml /etc/mongrel_cluster/project_name.yml

Then open your httpd.conf file for apache configration:

<Proxy balancer://project_name>
BalancerMember http://127.0.0.1:3000
BalancerMember http://127.0.0.1:3001
BalancerMember http://127.0.0.1:3002
</Proxy>

<VirtualHost *:80>
ProxyPreserveHost On
# Avoid open you server to proxying
ProxyRequests Off
# Options +FollowSymLinks
RewriteEngine On

RewriteRule ^/(images|stylesheet|javascript|html)/?(.*) /home/siwan/project_name/public/$0 [L]
ServerAdmin siwan@yahoo.co.in
DocumentRoot /home/project_name/
ServerName example.com
RewriteRule  ^/(.*)$  balancer://project_name%{REQUEST_URI} [P,QSA,L]
</VirtualHost>

Restart the apache server
#/etc/init.d/httpd restart

Command for restart the mongrel servers from any where
# mongrel_rails cluster::restart -C /etc/mongrel_cluster/project_name.yml

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