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First, hot-deploy doesn't always work. We spent so much time to make sure every new module is loaded and decided it's not worth the trouble. So what you are doing may sound bad but it's the most reliable way to deploy a new WAR.
Our current approach is to use a switch with load-balancer in front of all servers. We run at least 2 instances of the application servers. When we shutdown one server for maintenance, the traffic automatically goes to the other one.
Some of the switches are really inexpensive. If you don't have enough load to justify a new box and your 2 instances can run on the same box.
In some circumstances, the switches can actually save money. For example, we have a SSL page that used to use 6 boxes and now it runs fine on 2 boxes with SSL acceleration in the switch.
Usually it's possible to optimize start-up time. Our web application starts with Jetty in 5-7 seconds. Other Java web servers are worse, because they start very slow.
Also, as I'm aware (not I did it), the front-end web server (such as apache, we use lighttpd) could be configured to hold request some period of time (up to 30 seconds on ours) while the Jetty is not ready. So, we just easily restart the Jetty while deploying, and users just have several seconds delay in worst case, which usually just looks like an Internet connection glitch.