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 traditional Unix filesystem principles, and was designed by Rémy Card to overcome certain limitations of the MINIX file system.[4][2] 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]

ext
Developer(s)Rémy Card
Full nameextended file system
IntroducedApril 1992 (1992-04) with Linux 0.96c
Discontinued14 January 1997 (1997-01-14)
with Linux 2.1.21
Preceded byMINIX file system
Succeeded byext2
Structures
Directory contentsTable
File allocation
  • Free space: Linked list[1]
  • Metadata: Table
Bad blocksTable
Limits
Max volume size2 GB[2]
Max filename length255 characters[3]
Features
File system
permissions		Unix permissions
Transparent
encryption		No
Copy-on-writeNo

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 In 1993, it was superseded by both ext2 and Xiafs, which competed for a time, but ext2 won because of its long-term viability: ext2 remedied issues with ext, such as the immutability of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.[5]

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

References
  1. "freelists.c - fs/ext/freelists.c - Linux source code (2.1.20)". Bootlin. Retrieved 14 May 2023.
  2. Jones, M. Tim (17 February 2009). "Anatomy of ext4". IBM Developer Works. Retrieved 8 February 2012.
  3. "ext_fs.h - include/linux/ext_fs.h - Linux source code (0.96c-patch2)". Bootlin. Retrieved 14 May 2023.
  4. "Rémy Card (Interview, April 1998)" (in French). April Association. 19 April 1999. Archived from the original on 4 February 2012. Retrieved 8 February 2012.
  5. Card, Rémy; Ts'o, Theodore; Tweedie, Stephen. "Design and Implementation of the Second Extended Filesystem". Archived from the original on 4 February 2012. Retrieved 8 February 2012. First published in First Dutch International Symposium on Linux. State University of Groningen. 1995. ISBN 90-367-0385-9.
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