Operating System: File System Structure

• An operating system (OS) manages computer hardware and software resources, providing services to computers and acting as an intermediary between applications and hardware.

Document System

• A file system organizes and manages data on storage devices like hard drives or pen drives.
• It provides efficient user access for data storage, location, and recovery.
• Most operating systems use layers for each task, including file systems, with each layer responsible for specific functions.

File-System Structure

• A file is a logical storage unit and a collection of related information.
• The file system is organized into layers within the storage unit.
• File System Structure refers to how files and directories are organized and stored on the physical storage device, including the layout of data structures like directory structure, file allocation table, and inodes.
• Operating Systems impose one or more file systems to allow data to be stored, located, and retrieved easily.

Layered File System

• The file system is divided into different layers, each with specific functionality.
• When an application requests information, the request is sent to the information source, which contains metadata.
• The hard drive is divided into parts and sectors and the installation file module determines which physical block the application needs.
• The data is divided into several logical blocks, stored, and retrieved from the hard drive, which also manages free space.
• The installation file module passes physical block information to the underlying file, which issues commands to the I/O controller.
• The I/O control has access rights to the hard disk and uses drivers for I/O management and interrupt handling.
• Unix uses the Unix File System (UFS).
• Windows supports FAT, FAT32, and N-TFS.

FAT (File Allocation Table)

• A file created by Microsoft to support small disks and simple formats.
• It uses a table to keep track of the volume's heaps.
• FAT is used to overcome the shortcomings of mounting partition names and has slightly faster access.
• The system creates an index table for data stored.
• The index table contains the entry data for each data.
• The operating system searches for the group number of each extension of the file until it reaches the end.
• It supports a maximum volume of 4 GB.

Inode

• A file structure in the UNIX operating system that contains important file information.
• When a file system is created in UNIX, a certain number of inodes are also created.
• About 1% of the file system’s disk space is allocated to the inode table.

Different Types of File Systems

• A file system organizes/manages data on storage device. Many types exist, each with unique features and OS compatibility:
• FAT (File Allocation Table): FAT12, FAT16, FAT32.
• Created by Microsoft to support small disks and simple folder structure and FAT32 is used for large partitions.
• NTFS (New Technology File System):
• Developed by Microsoft, NTFS is more reliable and advanced than FAT.
• Supports features such as encryption, compression, disk quotas.
• For use with modern Windows operating systems.
• exFAT (Extended File Allocation Table):
• Optimized for flash memory devices such as USB flash drives and SD cards.
• NFTS is not suitable for such operations, so exFAT is better.
• HFS (Hierarchical File System):
• Can refer to tree-like groups of files and folders, or HFS, which is the file system used by MacOS.
• ReFs (Resilient File System):
• The latest file system designed for elastic, high-throughput data availability in big data environments.