I am trying to mount a share located on Server1 using NFSv4, instead of NFSv3. The host server is running RHEL 5.1 (don't ask), and the client is running RHEL 7.3. I am able to mount it using NFSv3 without problems, but I am doing a ton of file moving daily with small files, and I think performance would improve significantly if I used NFSv4.
I am running the following command:
mount -v -type nfs4 server1:/export/foo /nfsmnt/foo
And I get:
mount(2): Input/output error
mount system call failed
If I do
mount -v -type nfs -o nfsvers=3 server1:/export/foo /nfsmnt/foo
It works just fine.
I have confirmed that NFSv4 is supported on both client and server, using rpcinfo -p. The firewall is currently turned off on both.