The Fourth Extended File System (ext4 or ext4fs) is a successor to the ext3 file system. Just like ext3, it is a journaling file system. It offers better performance and improved reliability than ext3.
ext4 supports the following features:
- backward compatibility – ext4 is backward compatibile with both ex2 and ext3.
- persistent pre-allocation – ext4 can pre-allocate on-disk space for a file.
- unlimited subdirectories – ext4 supports an unlimited number of subdirectories.
- extents – ext4 uses extents to divide large files.
- faster file system checking.
- improved timestamps.
ext4 supports filenames up to 255 characters, maximum file size of up to 16 TB, and file system of up to 1 EB (1 billion gigabytes).