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 compatibilityext4 is backward compatibile with both ex2 and ext3.
  • persistent pre-allocationext4 can pre-allocate on-disk space for a file.
  • unlimited subdirectoriesext4 supports an unlimited number of subdirectories.
  • extentsext4 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).

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