Liferay Portal is configured for a single-server environment, which comes out of the box. When your site traffic starts increasing, you need to increase your server size as per the requirement. Here comes the Liferay Portal cluster design, which allows you to route the site traffic in different servers.
Liferay Portal works perfectly in a cluster of multiple machines—a horizontal cluster or in clusters of multiple VMs on a single machine, that is, a vertical cluster or a mixture of the two.
Let's take a scenario where you have installed Liferay on different server nodes. Now to make the cluster environment, you need to define several optimizations and configurations.