255 bytes (fewer for multibyte character encodings such as Unicode)
Allowed filename characters
All bytes except NULL ('\0') and '/' and the special file names "." and ".." which are not forbidden but are always used for a respective special purpose.
Features
Dates recorded
modification (mtime), data or attribute modification (ctime), access (atime), delete (dtime), create (crtime)
FreeBSD (full read/write support since version 12.0)
macOS (read-only with ext4fuse, full with ExtFS)
Windows (read–write without journaling with ext2fsd)
KolibriOS (read-only)
ext4 (fourth extended filesystem) is a journaling file system for Linux, developed as the successor to ext3.
ext4 was initially a series of backward-compatible extensions to ext3, many of them originally developed by Cluster File Systems for the Lustre file system between 2003 and 2006, meant to extend storage limits and add other performance improvements.[4] However, other Linux kernel developers opposed accepting extensions to ext3 for stability reasons,[5] and proposed to fork the source code of ext3, rename it as ext4, and perform all the development there, without affecting existing ext3 users. This proposal was accepted, and on 28 June 2006, Theodore Ts'o, the ext3 maintainer, announced the new plan of development for ext4.[6]
A preliminary development version of ext4 was included in version 2.6.19[7] of the Linux kernel. On 11 October 2008, the patches that mark ext4 as stable code were merged in the Linux 2.6.28 source code repositories,[8] denoting the end of the development phase and recommending ext4 adoption. Kernel 2.6.28, containing the ext4 filesystem, was finally released on 25 December 2008.[9] On 15 January 2010, Google announced that it would upgrade its storage infrastructure from ext2 to ext4.[10] On 14 December 2010, Google also announced it would use ext4, instead of YAFFS, on Android 2.3.[11]
^ abPreviously, Linux used the same GUID for the data partitions as Windows (Basic data partition: EBD0A0A2-B9E5-4433-87C0-68B6B72699C7). Linux never had a separate unique partition type GUID defined for its data partitions. This created problems when dual-booting Linux and Windows in UEFI-GPT setup. The new GUID (Linux filesystem data: 0FC63DAF-8483-4772-8E79-3D69D8477DE4) was defined jointly by GPT fdisk and GNU Parted developers. It is identified as type code 0x8300 in GPT fdisk. (See definitions in gdisk's parttypes.cc)
^"DiscoverablePartitionsSpec". freedesktop.org. Retrieved 7 April 2018.
^"ext4: Fix handling of extended tv_sec". Linux-stable kernel tree. Retrieved 14 February 2017.
^Mathur, Avantika; Cao, MingMing; Bhattacharya, Suparna; Dilger, Andreas; Zhuravlev (Tomas), Alex; Vivier, Laurent (2007). "The new ext4 filesystem: current status and future plans" (PDF). Proceedings of the Linux Symposium. Ottawa, ON, CA: Red Hat. Archived from the original (PDF) on 6 July 2010. Retrieved 15 January 2008.
^Torvalds, Linus (9 June 2006). "extents and 48bit ext3". Linux kernel mailing list.
^Ts'o, Theodore (28 June 2006). "Proposal and plan for ext2/3 future development work". Linux kernel mailing list.
^Leemhuis, Thorsten (23 December 2008). "Higher and further: The innovations of Linux 2.6.28 (page 2)". Heise Online. Archived from the original on 3 January 2009. Retrieved 9 January 2010.
^"ext4: Rename ext4dev to ext4". Linus' kernel tree. Archived from the original on 29 May 2012. Retrieved 20 October 2008.
^Leemhuis, Thorsten (23 December 2008). "Higher and further: The innovations of Linux 2.6.28". Heise Online.
^Paul, Ryan (15 January 2010). "Google upgrading to Ext4, hires former Linux Foundation CTO". Ars Technica.
^"Android 2.3 Gingerbread to use Ext4 file system". The H Open. 14 December 2010.
ext4 (fourth extended filesystem) is a journaling file system for Linux, developed as the successor to ext3. ext4 was initially a series of backward-compatible...
shutdown. Its successor is ext4. The performance (speed) of ext3 is less attractive than competing Linux filesystems, such as ext4, JFS, ReiserFS, and XFS...
e2fs programs) is a set of utilities for maintaining the ext2, ext3 and ext4 file systems. Since those file systems are often the default for Linux distributions...
This driver was deprecated in Linux version 6.9 in favor of the ext4 driver, as the ext4 driver works with ext2 filesystems. ext2 was the default filesystem...
to be added to the seconds field for the final time representation. The ext4 filesystem, when used with inode sizes larger than 128 bytes, has an extra...
more strictly by their on-disk format. For example, as of Linux 3.11, the ext4 file system limits the number of hard links on a file to 65,000. Windows...
the second extended file system. ext3, the third extended file system. ext4, the fourth extended file system. List of file systems Comparison of file...
distribution (using the ext4 file system) in a virtual machine under his/her production Windows environment (using NTFS). The ext4 file system resides in...
across multiple leaf and index blocks. HTree indexes are used in the ext3 and ext4 Linux filesystems, and were incorporated into the Linux kernel around 2.5...
Control". Microsoft Docs. 25 March 2021. Retrieved 2022-08-14. "Ext4 Disk Layout". "Ext4 Metadata Checksums". Mark Russinovich (February 2007). "Windows...
system, but many Linux distributions support some or all of ext2, ext3, ext4, Btrfs, ReiserFS, Reiser4, JFS, XFS, GFS2, OCFS2, and NILFS. It is possible...
name. As of version 1.5.3 it can also recover files from Ext2, Ext3 and Ext4 file systems of Linux. As with other file recovery programs Recuva works...
system family. It facilitates read and write access to the ext2, ext3 and ext4 file systems. The driver can be installed on Windows 2000, Windows XP, Windows...
Office Yes No Yes Yes (64 MB) No Yes Yes FAT32, NTFS, HFS+, APFS, ext2, ext3, ext4 and ReiserFS Yes Yes Yes Trialware AOMEI Yes No No No No Yes No No No No...
attributes depends on support by the underlying filesystem (such as FAT, NTFS, ext4) where attribute data must be stored along with other control structures...
forensics context. PhotoRec is shipped with TestDisk. FAT, NTFS, ext2/ext3/ext4 file systems store files in data blocks (also called data clusters under...
with the modern features of ZFS or Btrfs, and the speed and performance of ext4 or XFS. Bcachefs is a copy-on-write (COW) file system for Linux-based operating...
the "all-purpose all-platform filesystem" since 28 Jun 2023, succeeding Ext4. XFS is a 64-bit file system and supports a maximum file system size of 8...
more than 60 bytes ("fast symbolic links"). Ext4 has a file system option called inline_data that allows ext4 to perform inlining if enabled during file...
being written to. Many journal implementations (such as the JBD2 layer in ext4) bracket every change logged with a checksum, on the understanding that a...
The Installable File System (IFS) is a filesystem API in MS-DOS/PC DOS 4.x, IBM OS/2 and Microsoft Windows that enables the operating system to recognize...
original on 2015-04-06. Retrieved 2023-06-16. Blocking during io_submit on ext4, on buffered operations, network access, pipes, etc. Some operations are...
Enterprise Linux 6 and other derivatives are based on Fedora 10. Support for ext4 filesystem Sugar Desktop Environment LXDE Desktop Environment (LXDE Spin)...
2008, the principal developer of the ext3 and ext4 file systems, Theodore Ts'o, stated that although ext4 has improved features, it is not a major advance;...
has online and automatic defragmentation available. Linux ext2, ext3, and ext4: Much like UFS, these filesystems employ allocation techniques designed to...
December 7, 2010. Ts'o, Theodore (December 12, 2010). "Android will be using ext4 starting with Gingerbread". Linux Foundation. Archived from the original...
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