The Failover Fallacy

One of the complaints that fans of expensive EJB platforms like to level against Tomcat is that it doesn't provide failover support.

By failover, they're referring to the capability to seamlessly move a session from one server to another if the first server goes belly up. Any server can offer the other kind of failover, which is dropping a dead server out of a server pool, if you use a smart switch.

Just how important is session failover? For most sites, not very. For example, suppose that you have a fairly unstable site, which results in a Web server crashing once a week (anything more frequent than that, and your site has no business being live). Further say that you have five servers and get around 100,000 users a day—a ...

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