Unmounting file systems

A user can issue an unmount through ISHELL, the TSO/E UNMOUNT command, automount, or a program that is written to use the unmount() function. This function is restricted to users with appropriate privileges.

Here is the syntax of the TSO/E UNMOUNT command, showing the parameters that are important to this discussion:

UNMOUNT FILESYSTEM(file_system_name)
        NORMAL | DRAIN | RESET | IMMEDIATE | FORCE | REMOUNT(RDWR | READ | SAMEMODE)

where:

FILESYSTEM specifies the name that was used when the file system was mounted.
NORMAL | DRAIN | RESET | IMMEDIATE | FORCE | REMOUNT(RDWR | READ) specifies the type of unmount to perform.