A new way to upgrade your production site

EC2’s new elastic ip feature changes the way you upgrade a production site:

If you then launch a fresh instance for an upgrade of your web site, you can bring the new instance up separately from your production site, and set up the new version of your site and test it thoroughly. When you’re happy with everything, you can reassign the IP address from the old instance to the new one, and within seconds your users will be accessing the new version of the site. (For a more in-depth description, see the earlier blog post.)

Should there be a problem, you can always reassign the IP back to the old instance while you fix the problem. This, by the way, is the power of cloud computing: you don’t upgrade your server in place, you grab a new one, and you leave the old one running until you’re sure the new one is stable and ready for production.