Apologies, I just realised that the share hasn't even been mounted - I tried to write to the folder that resides on a local system, hence root permissions.
I run the following on the client:
# mount -v -t nfs -o vers=3,sec=none 10.10.0.51:/vol/NFS_WEB /mnt/netapp_nfs/ mount.nfs: timeout set for Fri Jul 15 16:18:45 2016 mount.nfs: trying text-based options 'vers=3,sec=none,addr=10.10.0.51' mount.nfs: prog 100003, trying vers=3, prot=6 mount.nfs: trying 10.10.0.51 prog 100003 vers 3 prot TCP port 2049 mount.nfs: prog 100005, trying vers=3, prot=17 mount.nfs: trying 10.10.0.51 prog 100005 vers 3 prot UDP port 4046 mount.nfs: mount(2): Permission denied mount.nfs: access denied by server while mounting 10.10.0.51:/vol/NFS_WEB
The file /var/log/messages on the client says:
localhost kernel: RPC: server 10.10.0.51 requires stronger authentication.
The NetApp tells me that:
[FAS:nfsd.auth.status.bad:warning]: Client 10.10.0.147 has an authentication error 5
So I cannot even mount it now.