Somehow, this one slipped through the cracks. Sorry for the delay. Here is my take. Since you are migrating from a UNIx box to NetApp, I assume that you will use some tool like rsync. I would typically not suggest using mixed mode security style but this is a good use case. If you set the volume security style (technically it is qtree security /vol/<volume> <style>) to mixed then you can natively copy over the UNIX permissions. Using mixed mode allows for you to go in and convert the permissions from UNIX to NTFS very easily. Next, you can use something like NTFS Security 2.1 PoSH toolkit (see this thread) to read the current interpreted NTFS permissions (ONTAP does this natively) and then set whatever default ACLs or permissions that you would like. Alternately, the option would be to simply mount the CIFS share and manually adjust the permissions.
Mixed mode security applies the 'type' of security that was last used to edit the security of a file. Newly created files should be NTFS if they are made by a host accessing over NTFS. Older files retain UNIX permissions until they are changed with a host accessing via CIFS. Does that make sense?
Jeremy Goodrum, NetApp