As most of us know, VMware supports many storage protocols – FC, FCoE, iSCSI and NFS.
However, only NFSv3 was supported in vSphere 4.x and 5.x. NFSv3 has many limitations and shortcomings like:

• No multipathing support
• Proprietary advisory locking due to lack of proper locking from protocol
• Limited security
• Performance limited by the single server head

Starting with vSphere 6, VMware introduces NFSv4.1. Compared to NFSv3, v4.1 brings a bunch of new features:

• Session Trunking/Multipathing
  • Increased performance from parallel access (load balancing)
  • Better availability from path failover
• Improved Security
  • Kerberos, Encryption and Signing is supported
  • User authentication and non-root access becomes available
• Improved Locking
  • In-band mandatory locks, no longer proprietary advisory locking
• Better Error Recovery
  • Client and server not state-less any more, with recoverable context
• Efficient Protocol
  • Less chatty, no file lock heartbeat
  • Session leases

Note: NFSv4.1, does not support SDRS, SIOC, SRM and vVOLs.

Supportability of NFSv3 and NFSv4.1:

• NFSv3 locking is not compatible with NFS 4.1
  • NFSv3 uses propriety client side locking
  • NFSv4.1 uses server side locking
• Single protocol accessforadatastore
  • Use either NFSv3 or NFSv4.1 to mount the same NFS share across all ESXi hosts within a vSphere HA cluster
  • Mounting one NFS share as NFSv3 on one ESX host and the same share as NFSv4.1 on another host is not supported!

Kerberos Support for NFSv4.1:

• NFSv3 only supports AUTH_SYS
• NFSv4.1 support AUTH_SYS and Kerberos
• Requires Microsoft AD for KDC
• Supports RPC header authentication (rpc_gss_svc_none or krb5)
• Only supports DES-CBC-MD5
  • Weaker but widely used
  • AES-HMAC not supported by many vendors

Implications of using Kerberos:

• NFSv3 to NFSv4.1
  • Be aware of the uid, gid on the files
  • For NFSv3 the uid & gid will be root
  • Accessing files created with NFSv3 from NFSv4.1 – Kerberized client will result in permission denied errors
• Always use the same user on all hosts
  • vMotion and other features might fail if two hosts use different users
  • Host Profiles can be used to automate the usage of users