I am using OES 2 SP1 (on SLES10 SP2 x64). I wanted to use a native Linux
file system, XFS, for a file share (however the issue is not confined to
XFS, for instance the problem exists in ext3 too).

I wanted to share out the files using Samba and using eDirectory users.
This works fine. However I wanted some fairly granular file rights which
are posing a problem. They aren't VERY granular as would be easy to
implement using NSS - all I want to do is to have directory A accessible
by group X and group Y and to have directory B accessible by group X only
- where groups X and Y are NOT the primary group of the LUM users

Taking Samba out of the equation for a moment I did some experimentation
just from a shell using simple tools like "su", "cd", "ls" etc. I have
found that if I use POSIX ACL's to assign a group file permissions to a
directory on XFS that it only works if the group is the user's primary
group. If I assign POSIX ACL rights to the user it works, to the primary
group it works but to a secondary group it does not work ("Access
Denied"). I believe my understanding of POSIX ACL's is not at fault here
because if I do the same experiment with a local UNIX user (in the /etc/
passwd file) and a local UNIX group (in the /etc/group) file then the
POSIX ACL's work exactly as I would expect. So it appears that there may
be a bug in LUM or maybe I just haven't configured something that I need
to in LUM to make POSIX ACL's work exactly as they do for local users.
Does anyone have any idea what the problem is?