Ext2 is a general-purpose file system with POSIX semantics. It was originally developed as part of the Linux kernel, and was the default file system for many GNU/Linux distributions until it was superseded by Ext3. Full or partial implementations exist for a number of other operating systems.
With a block size of 4KB the maximum size of an Ext2 volume is 16TB and the maximum size of an individual file is 2TB. Filenames are limited to 255 bytes in length, with only two characters (forward slash and null) forbidden. The maximum number of files in a directory is limited by performance considerations and it is best to avoid more than a few thousand.
The main drawback of Ext2 in comparison to the alternatives now available is its lack of support for journalling. This makes it vulnerable to corruption if it is not cleanly unmounted. For this reason Ext2 is not usually the best choice for new installations, but it can still be useful:
- on storage devices (such as some types of flash drive) where the use of a journal would be undesirable, or
- where compatibility requirements rule out the use of a more capable alternative.
- Increase the size of an ext2, ext3 or ext4 filesystem
- Reduce the size of an ext2, ext3 or ext4 filesystem
- Reduce the space reserved for root on an ext2, ext3 or ext4 filesystem
- The Second Extended Filesystem (documentation)
- Ext4 (and Ext2/Ext3) Wiki
- Rémy Card, Theodore Ts'o and Stephen Tweedie, Design and Implementation of the Second Extended Filesystem, Proceedings of the First Dutch International Symposium on Linux
- Ext2fs Home Page