[gpfsug-discuss] Samba mapping of "special" SID entries

Orlando Richards orlando.richards at ed.ac.uk
Fri Jun 22 15:52:34 BST 2012

Hi all,

Has anyone bumped up against the "nfs4: special" option in GPFS/Samba 
deployments which manipulates how the "owner" and "group owner" (and 
"everybody") behaviour is mapped to ACLs when accessed via the samba stack?

In particular, with the "default" setting (if one blindly follows the 
worked examples on this) of nfs4: special, if a user adds themselves 
specifically to an ACL, this creates an entry:


rather than:


which has the knock-on effect that if a file/folder is created under 
this ACL by a different owner (or if ownership changes), the person who 
put said ACL on to the file/folder no longer has access. Most people 
find this confusing (which is putting it politely).

To further complicate matters, the "special" windows SID's*[1] - such as 
"CREATOR/OWNER" -  don't seem to work properly in the ctdb/samba/gpfs 
stack (I don't know if they do in "normal" samba though). IBM don't 
support CREATOR/OWNER in SONAS*[2] - so it's not just me!

So my question is - has anyone else been looking into this at all, and 
if so, do you have any sage words of wisdom to offer?


*[1] http://support.microsoft.com/kb/163846

    Dr Orlando Richards
   Information Services
IT Infrastructure Division
        Unix Section
     Tel: 0131 650 4994

The University of Edinburgh is a charitable body, registered in 
Scotland, with registration number SC005336.

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