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How does the vSphere 6 release affect storage?

VSphere 6 supports NFS 4.1, but there are caveats to using multiple versions of NFS that storage administrators should be aware of.

If you take Virtual Volumes out of the equation, there are a number of small challenges that data storage administrators might encounter with the vSphere 6 release.

One storage issue that occasionally proves to be problematic is vSphere 6 support for NFS 4.1. Previously, vSphere supported only NFS version 3. While support for a newer version of NFS is not a problem in and of itself, issues can occur if you use multiple NFS versions.

When you create a new datastore, the New Datastore wizard asks if you want to use NFS 3 or NFS 4.1. However, the NFS version screen also displays the following warning message: "Use only one NFS version to access a given datastore. Consequences of mounting one or more hosts to the same datastore using different versions can cause data corruption."

There are also some vSphere features -- such as Storage DRS, storage I/O control, Site Recovery Manager and Virtual Volumes -- that cannot be used with NFS 4.1. Legacy fault-tolerance mechanisms cannot be used with NFS 4.1 either, but the newer fault-tolerant mechanisms available with the vSphere 6 release do work with NFS 4.1.

Security is another issue that must be addressed when making the transition to NFS 4.1. Although NFS 4.1 still supports the AUTH_SYS mechanism, Kerberos is preferred because it is far more secure. If you create a new datastore that uses NFS 4.1, the New Datastore wizard will give you the option to use Kerberos-based authentication. If you choose Kerberos, there are two situations you need to be aware of:

  • To use Kerberos authentication, any host that mounts the datastore has to be a member of an Active Directory domain. The wizard will warn you of this issue.
  • An NFS user is defined on each host, so you must configure each host to use the same user or some management tasks may fail.

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