RobChang,  What I had to do to solve this issue was disable inheritance on the child folder this file was placed in.  After doing so the permissions on this file stopped reverting back to the permissions of the child folder it was placed in after the user made changes to it.   Thank you,
Isilon Community,  I know this is a long shot and this might not even be a Isilon issue, but I will see if anyone know what this could be.  I have a user that created a file within a folder fairly deep with in the /ifs/data directory.  This is nothing new, but what is... when I change the permissions to this .xlsx file that this user wants me to lock down the next day the inheritance permissions automatically get pushed down to it.  HUH?!  I have no clue what is going on.  So what I did as a test I created a copy of the same file in the same location but added "FILENAME-TestPermissions.xlsx" to the file name.  Wouldn't you know the next day the explicit permissions I set stayed the same for the "FILENAME-TestPermissions.xlsx" file.   Ok, this is great!  So the user thought that maybe they could just transfer their information to the "FILENAME-TestPermissions.xlsx" file and all would be well.  I thought the same until the user performed the task and saved the file, when they went to look at the permissions the very thing that kept happening to the original file happened to the "FILENAME-TestPermissions.xlsx" file.  the folder inheritance had gotten pushed down to the "FILENAME-TestPermissions.xlsx" file.  Weird, and I don't have an explanation.  Has anyone see this before?  If so where should I start looking for a fix?  FYI,  NO there is no permission repair job running... at least not one that I configured as the Storage Engineer/Administrator.    Thank you,
User Permissions and inheritance being automatically pushed