Extended file system

The extended file system, or ext, was implemented in April 1992 as the first file system created specifically for the Linux kernel. It has metadata structure inspired by the traditional Unix File System (UFS) and was designed by Rémy Card to overcome certain limitations of the MINIX file system.[1] It was the first implementation that used the virtual file system (VFS), for which support was added in the Linux kernel in version 0.96c, and it could handle file systems up to 2 gigabytes (GB) in size.[2]

Full nameExtended file system
IntroducedApril 1992 with Linux
Directory contentsTable
File allocationbitmap (free space), table (metadata)
Bad blocksTable
File system permissionsPOSIX
Transparent encryptionNo

ext was the first in the series of extended file systems. In 1993 it was superseded by both ext2 and xiafs, which competed for a time, but ext2 won because of its long-term viability: ext2 remedied issues with ext, such as the immutability of inodes and fragmentation.[3]

Other extended file systems

There are other members in the extended file system family:

  • ext2, the second extended file system
  • ext3, the third extended file system.
  • ext4, the fourth extended file system.

See also


  1. "Rémy Card (Interview, April 1998)". April Association. April 19, 1999. Archived from the original on February 4, 2012. Retrieved 2012-02-08. (In French)
  2. Jones, M. Tim (February 17, 2009). "Anatomy of ext4". IBM Developer Works. Retrieved 2012-02-08.
  3. Card, Rémy; Ts'o, Theodore; Tweedie, Stephen. "Design and Implementation of the Second Extended Filesystem". Archived from the original on 2012-02-04. Retrieved 2012-02-08. First published in First Dutch International Symposium on Linux. State University of Groningen. 1995. ISBN 90-367-0385-9.
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