Liferay was built from the ground up to be used by application service providers. By installing multiple portal instances a complate isolation of the users, organizations, locations, communities and any other data created through Liferay's portlets is achieved. This is possible because all of the tables used by Liferay have a column called companyId that identifies the portal instance to which the entry belongs.

The following is a sample list of portals running off of one portal instance hitting one database and shows the capabilities of Liferay: http://demo.liferay.net, http://my.ccuc.net, http://my.3sixteen.com, http://www.gatewayfriends.org, http://www.jasonandiris.com. Users in each of these portals have no information about the other portals. They are separated by domain and each portal exists in its own space based on the company's id.

The installation of multiple portal instances is specific to each application server. Following detailed steps for the most common ones are provided. These instructions assume that one instance of Liferay Portal is already installed and is working. Two example domain names, www.alpha.com and www.beta.com will be used, change them with the real ones for a live environment. Finally, although these instructions are for only two instances, the same process can be applied to add as many instances as supported by the system resources.