RHEL7.4: NFS mount hangs while mounting a EMC Vmax share - NFS server reply to DESTROY_CLIENTID with NFS4ERR_CLIENTID_BUSY

Issue

• Unable to mount EMC Isilon NFS server after upgrading to RHEL7.4. 'vers=' commandline was not specified and the EMC Isilon either was only configured for 4.0 or only supported 4.0.
• The NFS man page states if there is no version specified the NFS client should negotiate a lower protocol version, however this was not done and instead the mount failed.
• On EMC Vmax with eNAS NFS server, a mount will just hang and never complete, and we have to CTRL-C the mount command.

# mount -v nfs-server.example.com:/export /mnt
mount.nfs: timeout set for Thu Aug  3 08:59:32 2017
mount.nfs: trying text-based options 'vers=4.1,addr=10.1.1.1,clientaddr=10.2.2.2'
^C