It is possible with the VNX platform (file) using file extension filters.    I do not believe Isilon has anything similar to that.
My company just purchased two Isilons,two VNX7500s and VPLEX. We are looking to migrate our home folders, department folders and profile folders from Windows Storage Server 2003 to either VNX CIFS or Isilon CIFS but are concerned about which is considered the best platform for this. We currently use storage quotas and, more importantly, file content filtering on the user home folders so we can prevent users from filling expensive storage with all their home movies, photos and music. Our EMC sales team struggled with an answer to this question. I believe the VNX can do this, not gracefully, but possible.  Thanks in advance for any insight you might provide, Frank
Can Isilon Filter Content Types on CIFS Shares?