Understanding the scenarios in which SharePoint is not supported are extremely important when designing SharePoint farms; as if you experience any trouble with your environment and need to get Microsoft support involved, they typically won’t be able to help you, and will instead ask you to get your environment in a supported state.

On SP2013 it is important to note that these scenarios are not supported:

• Installation on a machine that is not joined to a domain (i.e. a machine in a workgroup)
• Installation on a Virtual Machine (VM) that uses Dynamic Memory
• Installation on a Domain Controller (only supported in development environments – not production)
• Installation on Resilient File System (ReFS). ReFS is a new file system built into Windows 8 that is designed to work as advertised (be more resilient to common errors that would cause corruption or availability issues). Only NTFS is supported for SP2013 at the moment.
• Installation on a Windows Web Server

Here’s the link to the Original support article.