If the Interix subsystem encounters a user or group for which
it cannot compute a UID or GID that is unique, a log entry will be
made in the Windows application event log. When you first install
Windows Services for UNIX, and periodically thereafter, you should
check the application event log to ensure that all users and groups
are being assigned valid UID and GID values.
When an attempt is made to access a file by using Client for
NFS, the Interix subsystem uses User Name Mapping to map Windows
users and groups to their corresponding UNIX user identifier (UID)
and group identifier (GID) values. This mapping is done solely for
the purpose of communicating with network file system (NFS)
servers. If no User Name Mapping server is available, the Interix
subsystem will not be able to map users and groups when accessing
NFS resources. To prevent this, be sure that a properly configured
server running User Name Mapping is available and that Windows
Services for UNIX is configured to use that server. For more
information, see Set up
authentication using User Name Mapping.