Just as a file must be opened before it is used, a file system must be mounted before it can be available to processes on the system.
More specifically, the directory structure may be built out of multiple volumes, which must be mounted to make them available within the file-system name space.
The mount procedure is straightforward.
The operating system is given the name of the device and the mount point—the location within the file structure where the file system is to be attached. .
Some operating systems require that a file system type be provided, while others inspect the structures of the device and determine the type of file system.
Typically, a mount point is an empty directory.Forinstance,ona UNIXsystem,afilesystemcontainingauser’shome directories might be mounted as /home; then, to access the directory structure within that file system, we could precede the directory names with /home,as in /home/jane. Mounting that file system under /users would result in the path name /users/jane, which we could use to reach the same directory.
Next, the operating system verifies that the device contains a valid file system.
It does so by asking the device driver to read the device directory and verifying that the directory has the expected format.
Finally, the operating system notes in its directory structure that a file system is mounted at the specified mount point.
This scheme enables the operating system to traverse its directory structure, switching among file systems, and even file systems of varying types, as appropriate.