For multiprotocol environments (unix and windows users accessing the same files/directories) usermapper should not be your choice. In such environments it should be disabled or only used as a last resort.

Typically you will run into issues regarding the UIDs and GIDs, because there must be a central tools which will map usernames against UIDs and GIDs and the other way round, even if the naming is different 

You need some naming service (f.e. LDAP, NIS, IdMU, local files) which will provide a mechanism for looking up user and system informations.

Please check the manuals "Configuring VNX User Mapping" and "Configuring VNX Naming Services"

Out of my knowledge,

If a windows user writes a file, and usermapper was responsible for the UID mapping, then the group written into the filesystem will be "Domain Users". And it will be the same for all usermapper users.

But please test this.

Peter,

Thanks for your response. This is “only used as a last resort.”

So assume I have read the manuals ( I have ), been forced down this road ( I have ), is there an answer to my question ?

See the cifs acl.useUnixGid

name = useUnixGid

facility_name = cifs

default_value = 0

current_value = 1

configured_value =

user_action = reboot DataMover

change_effective = reboot DataMover

range = (0,4294967295)

description = NA

☹

Alas the description is a bit of a black hole. Is it documented anywhere ?

From the Paramters Guide:

Sets the group identifier (GID) mapping for file system objects created on a Windows client.

0 = Assign the GID of the Windows primary domain group to which the user belongs.

1 = Assign the Windows user’s GID (as found in the GID field of the .etc/passwd file, NIS database entry, or Active Directory).