Some Basic Information About File System

The file system is the primary means of data management. Without it, data stored in a storage medium would be a large body of data, so that it would be hard to tell where one piece of data stops, and the next one starts. But with the file system, the data can be easily isolated and recognized by dividing the data into parts and give each part a name.

What Is a File System?

In a computer, a file system or filesystem is the way to name, recognize, and retrieve files. Generally speaking, it is a structured representation of the data and a set of metadata that describes this data.

Files in the file system are divided into parts called directories, which contain other directories and files. Nowadays, NTFS is the most commonly used file system.

Structure of File System

There are two or three layers in a file system, which are sometimes explicitly separated but functionally combined.

The logical file system

It is the first layer of a file system responsible for interacting with the user application. It offers the API(application program interface) for file operations and passes the requested operations to the layer below it for processing.

The virtual file system

The virtual file system is the second layer that supports multiple concurrent instances of physical file systems; each is called a file system implementation.

The physical file system

As the third option layer, the physical file system is related to the physical operation of the storage media and responsible for blocks’ physical placement. It handles physical blocks that are being read or written, as well as buffering and memory management.

Types of file systems

File System in Windows

There are two major file systems in Microsoft Windows: NTFS and FAT. And Microsoft developed ReFS as a new generation file system.

NTFS – New Technology File System

Introduced with Windows NT in 1993, NTFS is the primary and the most widely used file system for Windows computer users. It is reliable and supports multiple features, including encryption, access control, etc.

Each of the Files is stored in NTFS as a file descriptor in the Master File Table. The Master file table includes entries for all information about the files: name, size, allocation, etc. It supports support extremely high-capacity data storage for its 48-bit and 64-bit values to reference files.

FAT – File Allocation Table

Exists since the 1980s, FAT is one of the simplest types of the file system, which consists of the block allocation tables, the file system descriptor sectors, and common storage space to store files and folders.

FAT stores files in directories, which is a set of 32-byte records, each is defining a file or a file’s extended attributes. The numbers of FAT12, FAT16, FAT32 represent the number of bits to enumerate the file system block. It means that FAT12 can use at most 4096, and FAT16 and FAT32 can use a maximum of 65536 and 4294967296 different block references accordingly.

Microsoft introduced exFAT to break the size limitations of files or partitions.

ReFS – Resilient File System

As the latest generation, Microsoft introduced it with Windows 8, and it is currently available for Windows 10. It has a high tolerance to failures caused by new features in the system.

Unless this storage space and the data are overwritten, different locations of the file system store a large number of older backups, making it easy to recover files.

File systems in macOS

There are two types of the file system in Apple’s macOS: HFS+ and APFS.

HFS+

HFS+ used to be the primary file system of Apple products. Then APFS replaced it in macOS High Sierra, and advanced server products also apply Apple Xsan.

HFS+ uses B-trees to place and locate files. Volumes are divided into sectors, 512 bytes in size, which are then grouped into allocation blocks. The number of these sectors depends on the size of the whole volume.

Journaling improves data reliability so that it is possible to track all changes to the system and quickly return to work in case of an unexpected event.

Other supported features include access control, logical volume encryption, data compression, and hard links to directories, etc.

APFS – Apple File System

APFS is designed to address underlying issues in its predecessor and to efficiently work with SSD(solid-state drive) and modern flash storage.

The APFS container keeps all the metadata and file contents related to files, folders, and other APFS structures.

File systems in Linux

Ext

This file system belongs to proactive developments and improvements. It is often used for most Linux installations as a “root” file system. Ext2, Ext3, and Ext4 are the primary file system of Linux.

ReiserFS

It is an available file system to store a large number of small files, which enjoys good capability but no longer receive active support.

XFS

Originally used on the company’s IRIX servers, XFS is now implemented in Linux. This file system offers excellent performance and is widely used to save files.

JFS

IBM developed JFS for the computing system of the company. JFS1 is the JFS, and the company released the second one, JFS2. It is currently open-source and applied in most modern Linux.

Btrfs

Oracle designed Btrfs since 2009, aiming to provide greater fault tolerance, easier management with better scalability and reliability.

Sum It UP!

Files system is a necessary and vital part of computers, which has many types. The above lists some main types of file systems according to the operating systems you are using. In a word, you will have an overall understanding of it after going through this page.