What are File Systems?
File systems are methods and data structures that an operating system uses to manage and organize data on storage devices, such as hard drives, SSDs, and USB drives. They define how data is stored, accessed, and organized, allowing users and applications to interact with files and directories in a coherent manner.
Feature of File System-
- Data Organization- File systems organize data into files and directories (folders), making it easy to manage and locate information.
- File Naming- They allow users to create, name, and modify files, following specific naming conventions and restrictions.
- Storage Management- File systems manage how space is allocated on storage devices, handling fragmentation and optimizing storage efficiency.
- Access Control- They enforce permissions and security, determining who can read, write, or execute files.
- Data Integrity- Many file systems include mechanisms for error detection and recovery, such as journaling. Which helps protect against data loss during unexpected shutdowns.
- Metadata Handling- File systems store metadata for each file. Metadata includes information such as size, creation date, modification date, and access permissions.
Key Terms-
- Fragmentation- When files are not stored in contiguous blocks in storage, leading to inefficiencies in space usage and performance.
- Journaling- Logging of changes made to file while under process to recover in case of System Failure.
- Versioning- Saves copies of files stored based on changes made in a timely manner to create a Backup.
- Inode- Index node, representation of a File or Directory based on Meta Data such as size, permission, location, etc.
File System Architecture-
It refers to how users and applications store, retrieve and manipulate files and directories efficiently. File Systems consists of Three Layers-
- Logical File System-
- This layer interacts directly with user applications and provides the interface for file operations such as creating, reading, writing, and deleting files.
- It manages file metadata and translates user requests into operations for the underlying layers to execute.
- Virtual File System (VFS)-
- The VFS serves as an abstraction layer that allows multiple types of file systems to coexist within the same operating system.
- It provides a unified interface for file operations, enabling applications to access files on different file systems seamlessly.
- Physical File System-
- This layer interacts directly with the hardware and manages the actual storage of data on the disk.
- It handles low-level operations such as allocating space, reading from and writing to the disk, and managing the physical layout of files.
Different Types of File System in Linux-
- ext- The original extended file system for Linux, designed to address the limitations of earlier file systems. It laid the groundwork for future ext versions.
- ext2- An improvement over Ext, this non-journaling file system introduced features like better performance and larger file sizes, making it suitable for Linux systems.
- Xiafs- A very infamous file system developed in the early 1990s which is no longer in use.
- ext3- The first journaling file system in the ext family, offering improved reliability by maintaining a journal to prevent data loss during crashes.
- JFS- Developed by IBM, this journaling file system is famous for its high performance and scalability, particularly in enterprise environments.
- ReiserFS- A journaling file system that features advanced storage techniques like tail packing, aimed at reducing fragmentation and improving performance.
- XFS- A high-performance 64-bit journaling file system, well-suited for large files and high concurrency, commonly used in enterprise applications.
- SquashFS- A read-only file system primarily used in embedded systems and live distributions, designed for low overhead and high compression.
- Reiser4- An advanced version of ReiserFS, offering enhanced features like improved performance and flexibility, though it has limited support across distributions.
- ext4- The successor to ext3, this journaling file system provides better performance, support for large files, and advanced features like delayed allocation and extents.
- btrfs- A modern file system for Linux with features such as snapshots, data integrity checks, and dynamic volume management, designed for flexibility and scalability.
- Bcachefs- A newer copy-on-write file system that aims to combine the best features of ext4 and btrfs, offering advanced capabilities like full filesystem encryption and snapshots.
- Other- Linux Support other file systems such as NTFS, exFAT, FAT32, etc. but these do not support standard Unix permission settings, thus they are mostly used for interoperability with OS.
Which File System is widely used in Linux and Why?
ext4 is widely used in Linux, due to several reasons such as
- Stability and Maturity: Ext4 has been around longer and users consider it as very stable and reliable. It has a proven track record in various environments, making it a go-to choice for many users and distributions.
- Backward Compatibility: Ext4 is backward compatible with ext3 and ext2, allowing for easier upgrades without data loss. This feature appeals to users who want to transition without significant risk.
- Performance: While other file systems unique features, ext4 provides a well-rounded performance suitable for most use cases. It balances speed, reliability, and efficiency, making it a practical choice for general-purpose use.
- Simplicity: Ext4 is simpler to configure and manage compared to other file systems, which have more complex features. Many users prefer the straightforward nature of ext4 for everyday tasks.
- Default Choice: Many Linux distributions have chosen ext4 as the default file system, leading to its widespread adoption. This choice influences new users and installations, reinforcing its popularity.
- Community and Support: A larger user base means more community support, documentation, and troubleshooting resources available for ext4, making it easier for users to find help when needed.