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We are currently using mod_jk and apache to load balance our tomcat servers. We would like to know what is the experience and comparison with the amazon AWS load balancer.

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It works fine and is very simple to setup. Only problem I found is that there is no way to attach a root domain name to Amazon's ELB because ELB IP's changes. For me this is critical so I'm testing other solutions like HA Proxy.

ELB + Elastic IP would be a great solution for load balancing.

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It changes, ok, so you setup a ELB you get ip x.x.x.x and in a few days you will have ip y.y.y.y? is that what you are saying, that is crazy. Thanks for your input. – Geo Jul 24 '09 at 17:13
Yes, if you only need subdomains it's ok (just add CNAME records to the public DNS name of your ELB) but for root domain names is a problem. You can read Amazon's answer to this issue here: – HD. Jul 24 '09 at 17:18

I am in the process of figuring out the same thing. My current plan of attack is to have an AWS load balancer pointing to 2 EC2 instances both running Apache (in this case with mod_proxy_ajp) and 2 Tomcat servers.

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Hellp PAS. Thanks for the input, so then each app server running mod_proxy_ajp will be a second load balancer? is that the rational? – Geo Jul 24 '09 at 17:13

I have found that most domain registrars offer basic DNS tools with domain redirection (HTTP 301) and thus you should be able to set your root entry (e.g. as a redir to or the like. This is all assuming that you are ok with the redir and don't need your site to respond to This would keep you from having to pay for another elastic IP as Amazon.

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Amazon just introduced VPC today. See link below:

You might be able to integrate with that to the current solution.

"Amazon Virtual Private Cloud (Amazon VPC) is a secure and seamless bridge between a company’s existing IT infrastructure and the AWS cloud. Amazon VPC enables enterprises to connect their existing infrastructure to a set of isolated AWS compute resources via a Virtual Private Network (VPN) connection, and to extend their existing management capabilities such as security services, firewalls, and intrusion detection systems to include their AWS resources. Amazon VPC integrates today with Amazon EC2, and will integrate with other AWS services in the future. As with all Amazon Web Services, there are no long-term contracts, minimum spend or up-front investments required. With Amazon VPC, you pay only for the resources you use."

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