Liferay Portal is one of the most flexible applications with regard to application server environment on the market today. You can install Liferay Portal on everything from a shared Tomcat installation to a multi-node cluster running a commercial application server, and on everything in between. In fact, Liferay is used successfully in all of these scenarios every day.
You will find that because Liferay is extremely flexible in its deployment options, it is easy to install as well. If you already have an application server, you can simply use the tools for deployment that came with your application server. If you do not have an application server, Liferay provides several application server bundles from which to choose. These are very easy to install and with a small amount of configuration can be made into production-ready systems.