Remember that each of the NFS client systems will determine the username by looking up the numerical UID locally using the local system's /etc/passwd, or in your centralized user database. The NFS server only stores the UID in numerical format, and does not know about usernames. This is also true for group names vs. GIDs.
In your case, serverA and serverB must have different usernames listed in /etc/passwd
To test this, use ls -n to display user and group IDs numerically, rather than converting to a user or group name in a long (-l) output. If the ls -n option is not available on AIX, consult the manpage for this feature.
To see the username-to-uid mapping, do one of the following on both serverA and serverB.
grep $THEUSERID /etc/passwd
Or, it's a good habit to use getent, since it works with /etc/password, and directory services (LDAP, etc.):
getent passwd $THEUSERID
The UIDs should be the same on both systems, but the usernames will be different.
Have a look at the map_static option in /etc/exports.
Or synchronize userids using NIS, LDAP, etc.
Best Answer
nfs4 does not use uid numbers but usernames. You can add to your
/etc/idmapd.confwhere
fredis the username on the remote, and localfred is the local username.