Operating Systems

ext4

Definition

The fourth extended filesystem (ext4) is a journaling file system for Linux, developed as the successor to ext3. It has become the default file system for many popular Linux distributions.

Why It Matters

ext4 brought significant improvements in performance, reliability, and scalability to the Linux world. It supports very large file sizes and volumes and uses techniques to reduce file fragmentation.

Contextual Example

When you install a Linux distribution like Ubuntu, the installer will typically format your root partition with the ext4 file system.

Common Misunderstandings

  • ext4 is a journaling file system, which helps protect against data corruption from unexpected shutdowns.
  • Newer file systems like Btrfs and ZFS exist, but ext4 remains a very popular, stable, and well-tested default choice.

Related Terms

Last Updated: December 19, 2025