We've got a number of shares, and the team assigned to manage them for the various end user groups messed up and gave a few users full rights to the very top of the share that they shouldn't have. 
If I attempt to use Windows Explorer to remove these users, it will break inheritance on the share because of modifying the root of the share. Windows suggests doing it locally, which of course on Isilon means the chmod command. 

Before messing about with a share that hundreds of users are using,  I created a test share (aptly named "test") and began experimenting with the chmod command on that share to educate myself.
I found an oddity running this chmod command:

chmod +a user DSP\\testuser allow dir_gen_all,object_inherit,container_inherit  /ifs/Isilon/smb/test

This should propagate down the share's dir tree as inheritance, but it doesn't.  Yet if I look in the root security properties of the share in explorer, it says that testuser permissions have "This folder, subfolders and files" selected, but yet no rights have propagated down to the subfolders.
The -R switch is recursive but doesn't work how I want, that recursively sets all rights explicitly..not what I need.

Lastly, in the OneFS admin page, ACL policy,  I enabled "Make ACL's inheritable" but that didn't work either;  I think that only applies to the POSIX bits. So I re-disabled that which was it's default state. 

I've been through the man page dozens of times, this is very odd.