Deployment of vSphere on IP based storage is becoming more common and  this paper provides a technical overview of deployment considerations  and best practices for running vSphere on Network File System shared  storage. It examines some myths and clears up confusion about various  perceptions that have existed in the past. Providing guidance and  references for further information and best practices that can be  followed to ensure a stable, high performance storage foundation for  vSphere virtualization environments.

http://vmware.com/files/pdf/VMware_NFS_BestPractices_WP_EN.pdf