cv
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Load balancer:
http://www.howtoforge.com/high_availability_loadbalanced_apache_cluster_p4
http://www.linuxvirtualserver.org/docs/ha/ultramonkey.html
http://httpd.apache.org/docs/2.2/mod/mod_proxy_balancer.html
Nagios:
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http://123shadow.wordpress.com/2009/01/30/nagios-tool-for-monitoring-multiple-remote-server/