10.1 File-System Structure

File structure

 1. Logical storage unit

 2. Collection of related information

File system resides on secondary storage (disks).

File system organized into layers.

File control block – storage structure consisting of information about a file.

Layered File System

A Typical File Control Block

In-Memory File System Structures

The following figure illustrates the necessary file system structures provided by the operating systems.

Figure 12-3(a) refers to opening a file.

Figure 12-3(b) refers to reading a file.

In-Memory File System Structures

Virtual File Systems

Virtual File Systems (VFS) provide an object-oriented way of implementing file systems.

VFS allows the same system call interface (the API) to be used for different types of file systems.

The API is to the VFS interface, rather than any specific type of file system.

Schematic View of Virtual File System