ext4

ext4 is a modern journaling filesystem for Linux that improves upon ext3 with better performance, larger file support, and increased reliability through extent-based allocation.

ext4 (Fourth Extended Filesystem) is the primary filesystem used on most Linux distributions today. It maintains backward compatibility with ext3 while adding significant improvements like support for files larger than 2 TB, faster fsck (filesystem checks), and better handling of fragmentation through extents—contiguous blocks of disk space allocated to a single file.

The filesystem uses a journal to log changes before committing them to disk, preventing data corruption during unexpected shutdowns or crashes. This journaling capability makes recovery fast and safe compared to older filesystems.

A typical ext4 setup might look like: /dev/sda1 formatted as ext4 with a journal enabled, automatically mounting at boot via entries in /etc/fstab. You can create one with mkfs.ext4 /dev/sdX and check its status with tune2fs -l /dev/sdX.

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