Oracle ASM File Access Control restricts the access of files to specific Oracle ASM clients that connect as SYSDBA.

An Oracle ASM client is a database, which is identified by the name of the user that owns the database instance home. Oracle ASM File Access Control uses this user name to identify a database. Oracle ASM File Access Control restricts access based on the operating system and effective user identification number of a database owner.

• Creation of New User Groups and Users for Separation of Database Administration Duties
  Oracle Database 19c provides access control to separate the roles on Windows.
• About Disk Group User Replacement
  The identity of an Oracle ASM user can be changed from one operating system user to another operating system user.
• About Changing File Access Control While the File is Open
  Oracle Database 19c enables users to change the ownership, permissions, or group membership of a file even while the file is open.