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| Developer(s) | Stephen Tweedie |
|---|---|
| Full name | Third extended file system |
| Introduced | November 2001 with Linux 2.4.15 |
| Preceded by | ext2 |
| Succeeded by | ext4 |
| Partition IDs | 0x83 (MBR) EBD0A0A2-B9E5-4433-87C0-68B6B72699C7 (GPT) |
| Structures | |
| Directory contents | Table, hashed B-tree with dir_index enabled |
| File allocation | bitmap (free space), table (metadata) |
| Bad blocks | Table |
| Limits | |
| Max volume size | 4 TiB – 32 TiB |
| Max file size | 16 GiB – 2 TiB |
| Max no. of files | Variable, allocated at creation time[1] |
| Max filename length | 255 bytes |
| Allowed filename characters | All bytes except NUL ('\0') and '/' |
| Features | |
| Dates recorded | modification (mtime), attribute modification (ctime), access (atime) |
| Date range | December 14, 1901 – January 18, 2038 |
| Date resolution | 1 s |
| Attributes | allow-undelete, append-only, h-tree (directory), immutable, journal, no-atime, no-dump, secure-delete, synchronous-write, top (directory) |
| File system permissions | Unix permissions, POSIX ACLs and arbitrary security attributes (Linux 2.6 and later) |
| Transparent compression | No |
| Transparent encryption | No (provided at the block device level) |
| Data deduplication | No |
| Other | |
| Supported operating systems | Linux, BSD, ReactOS,[2] Windows (through an IFS) |
ext3, or third extended filesystem, is a journaled file system that is commonly used by the Linux kernel. It used to be the default file system for many popular Linux distributions. Stephen Tweedie first revealed that he was working on extending ext2 in Journaling the Linux ext2fs Filesystem in a 1998 paper, and later in a February 1999 kernel mailing list posting. The filesystem was merged with the mainline Linux kernel in November 2001 from 2.4.15 onward.[3][4][5] Its main advantage over ext2 is journaling, which improves reliability and eliminates the need to check the file system after an unclean shutdown. Its successor is ext4.[6]
- ^ The maximum number of inodes (and hence the maximum number of files and directories) is set when the file system is created. If V is the volume size in bytes, then the default number of inodes is given by V/213 (or the number of blocks, whichever is less), and the minimum by V/223. The default was deemed sufficient for most applications. The max number of subdirectories in one directory is fixed to 32000.
- ^ "ReactOS 0.4.2 Released". reactos.org. Retrieved 17 August 2016.
- ^ Stephen C. Tweedie (May 1998). "Journaling the Linux ext2fs Filesystem" (PDF). Proceedings of the 4th Annual LinuxExpo, Durham, NC. Retrieved 2007-06-23.
- ^ Stephen C. Tweedie (February 17, 1999). "Re: fsync on large files". Linux kernel mailing list.
- ^ Rob Radez (November 23, 2001). "2.4.15-final". Linux kernel mailing list.
- ^ "Chapter 6. The Ext4 File System Red Hat Enterprise Linux 6".