vSphere 6 NFSv4.1

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

 

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