When NFS4 mount as nobody:nobody

The rpc.idmapd malfunctioned.

Cure:

service rpcidmapd restart

Work in: RHEL6

Also, check /var/log/message of the client to see which domain it expects.

If you see line as

rpc.idmapd[10199]: nss_getpwnam: name ‘user@domain’ does not map into domain ‘some_domain’

you’d go to the server and add line

Domain = some_domain

under the [General] section of /etc/idmapd.conf

and do

service rpcidmapd restart

service nfs restart

and go to the client side and remount the volume.

Things than will be fine.