Linux offers several filesystems, but among the most widely used and time-tested are the Extended File Systems — EXT2, EXT3, and EXT4. These are the default filesystems on many Linux distributions and have played a crucial role in the evolution of Linux storage and data management.
In this post, we’ll explore the history, development, usage, benefits, and drawbacks of each EXT filesystem.
EXT (Extended File System)
- Developer: Rémy Card
- Initial Release: April 1992
- Status: Obsolete
- Max File Size: 2 GB
- Max Volume Size: 2 GB
Overview:
EXT was the first filesystem specifically designed for the Linux kernel. It replaced the Minix filesystem, which lacked advanced features. EXT supported basic Unix-style permissions and provided better performance than its predecessor.
Limitations:
- No journaling support
- Lacked scalability
- No support for large files or volumes
Why it was important:
Although EXT is no longer in use, it laid the groundwork for the evolution of modern Linux filesystems.
EXT2 (Second Extended Filesystem)
- Developer: Rémy Card
- Initial Release: January 1993
- Status: Still used in special cases (e.g., USBs, boot partitions)
- Max File Size: 2 TB
- Max Volume Size: 32 TB
Overview:
EXT2 was a significant improvement over EXT. It became the default filesystem for many Linux distributions for years due to its stability and performance.
Key Features:
- No journaling (better performance in some contexts)
- Support for large file sizes and volumes
- Extensible design for future improvements
Usage Example:
mkfs.ext2 /dev/sdX1
Benefits:
- Simple structure and efficient storage
- Low write overhead (no journaling)
- Still useful for flash drives and SD cards
Drawbacks:
- Lack of journaling makes recovery difficult after crashes
- Higher chances of filesystem corruption on improper shutdown
EXT3 (Third Extended Filesystem)
- Developer: Stephen Tweedie
- Initial Release: November 2001
- Status: Legacy (still in use in older systems)
- Max File Size: 2 TB
- Max Volume Size: 32 TB
Overview:
EXT3 introduced journaling, which greatly improved reliability and crash recovery. It became the standard filesystem in enterprise-grade distributions like Red Hat Enterprise Linux.
Key Features:
- Journaling (metadata only, ordered, writeback)
- Backward compatible with EXT2
- Faster fsck (filesystem check) times
Usage Example:
mkfs.ext3. /dev/sdX1
Benefits:
- Reliable and stable
- Minimal learning curve for EXT2 users
- Easier recovery from crashes and power loss
Drawbacks:
- Slower than modern filesystems like EXT4 or XFS
- Lacks advanced features like extents, defragmentation, etc.
EXT4 (Fourth Extended Filesystem)
- Developer: Theodore Ts’o and Linux Kernel Community
- Initial Release: 2008 (Stable in Linux kernel 2.6.28)
- Status: Actively used and maintained
- Max File Size: 16 TB
- Max Volume Size: 1 EB (Exabyte, though practical limits are smaller)
Overview:
EXT4 is the most widely used Linux filesystem today. It is designed for scalability and performance while retaining backward compatibility with EXT3.
Key Features:
- Extents: Reduces fragmentation and speeds up file allocation
- Delayed Allocation: Improves performance and reduces fragmentation
- Journal Checksumming: More reliable journaling
- Faster fsck: Parallel file system checks
- Backward Compatibility: Can mount EXT3 and EXT2 filesystems
Usage Example:
mkfs.ext4. /dev/sdX1
Benefits:
- High performance and reliability
- Excellent journaling and recovery features
- Actively supported and widely adopted
- Scales well to large storage systems
Drawbacks:
- Not as feature-rich as Btrfs or ZFS (e.g., snapshots, compression)
- Delayed allocation can cause data loss in rare power failures
Comparison Table
| Feature | EXT2 | EXT3 | EXT4 |
|---|---|---|---|
| Journaling | ❌ | ✅ | ✅ |
| Max File Size | 2 TB | 2 TB | 16 TB |
| Max Volume Size | 32 TB | 32 TB | 1 EB |
| Performance | High (no journaling) | Medium | High |
| Use Case Today | USBs, Boot partitions | Legacy systems | Default on most Linux distros |
| fsck Time | Long | Medium | Fast |
| Fragmentation | Medium | High | Low (extents) |
Conclusion
The EXT family of filesystems has matured greatly over the decades. From EXT2’s simplicity to EXT4’s robust performance and reliability, these filesystems have been the backbone of Linux systems for years. While newer options like Btrfs, XFS, and ZFS offer more modern features, EXT4 remains the default choice for many because of its balance between stability, performance, and ease of use.
If you’re setting up a Linux system today, EXT4 is your safest and most compatible bet — especially for beginners and production systems alike…