Extended File System
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The extended file system was the first in a series of file systems created exclusively for Linux. It was one of the first filesystems to use the Linux Kernel's VFS API. ext (in version 1) is defunct and is no longer used in major Linux distributions.
Installation
Kernel
Be sure to have support for the needed version of the extended file system in the Linux kernel:
- ext2 - Introduced separate timestamps for file access, inode modification, and data modification. Does not support journaling. Upgradable to ext3 and ext4.
- ext3 - Extended file system version 3. Introduces (and requires) journaling. Upgradable to ext4.
- ext4 - Extended file system version 4. Supports fast fsck[1], native filesystem encryption[2]. Supports journaling, but also non-journaling.
Note
The original ext3 filesystem code was removed from the Linux Kernel with version 4.3, instead the ext4 filesystem code can now handle ext2, ext3 and ext4 filesystems. It will maintain compatibility if the filesystem is mounted as ext2 or ext3, and will provide upgradability when mounted as ext4. Additionally tune2fs can be used to add ext3- and ext4-specific features to an existing ext2 or ext3 filesystem, though certain hard limits will remain.
The original ext2 filesystem code remains available.
The original ext3 filesystem code was removed from the Linux Kernel with version 4.3, instead the ext4 filesystem code can now handle ext2, ext3 and ext4 filesystems. It will maintain compatibility if the filesystem is mounted as ext2 or ext3, and will provide upgradability when mounted as ext4. Additionally tune2fs can be used to add ext3- and ext4-specific features to an existing ext2 or ext3 filesystem, though certain hard limits will remain.
The original ext2 filesystem code remains available.
Note
Both ext2 and ext3 file timestamps are affected by the year 2038 problem, while ext4 is Y2k38-safe since 2016, Kernel 4.3.6 and e2fsprogs 1.43.
Both ext2 and ext3 file timestamps are affected by the year 2038 problem, while ext4 is Y2k38-safe since 2016, Kernel 4.3.6 and e2fsprogs 1.43.
USE flags
See the USE flags section of the e2fsprogs article.
Emerge
See the emerge section of the e2fsprogs article.
Usage
Mounting
See filesystem.
See also
- E2fsprogs — a suite of standard userspace programs for ext2, ext3, and ext4 filesystems.
- Btrfs — a copy-on-write (CoW) filesystem for Linux aimed at implementing advanced features while focusing on fault tolerance, self-healing properties, and easy administration.
- FAT — originally created for use with MS-DOS (and later pre-NT Microsoft Windows)
External resources
- https://ext4.wiki.kernel.org/ - The second, third, and fourth extended file system wiki.
- https://bugzilla.kernel.org/show_bug.cgi?id=23732 - The final fix for the Year 2038 problem, only for ext4.