ext3

Ext3, short for the third extended filesystem, is a journaling filesystem for Linux that built on ext2 by adding a robust metadata journal. It was introduced in 2001 by Stephen Tweedie to improve crash recovery while preserving backward compatibility with ext2. An ext2 volume can be upgraded to ext3 by enabling a journal; ext3 volumes can often be upgraded to ext4 with kernel support.

Key features of ext3 include journaling to ensure the integrity of the filesystem after power loss or crash, reduced fsck times after unclean shutdowns, and backward compatibility with ext2. It supports block sizes from 1 KiB to 4 KiB and file sizes that depend on the block size. It also introduced directory indexing via the HTree feature to speed up access to large directories. Ext3 provides several journaling modes: data=ordered (default), data=writeback, and data=journal, which control how much file data is journaled along with metadata.

Ext3 was widely adopted as the default filesystem in many Linux distributions through the 2000s and early 2010s. In the late 2000s, ext4 superseded ext3 as the default and added substantial improvements in speed, scalability, and features, but ext3 remains supported and in use for compatibility with existing installations and for stability.

Limitations and status: Development of ext3 has largely ceased in favor of ext4 and other filesystems. It remains a stable, reliable option, but newer filesystems offer larger sizes, extents, faster performance, and advanced features. Ext3 is valued for its maturity and compatibility with older systems.