As an SEO writer, it’s important to provide quick answers to questions in the opening paragraphs. So let’s start by answering – what is Ext4 and why is it considered the best file system for Linux?
What is Ext4?
Ext4 (Fourth Extended Filesystem) is a journaling file system for Linux. It is the default file system for many popular Linux distributions including Ubuntu, Fedora, and Linux Mint.
Ext4 was designed as an evolutionary successor to the Ext3 file system, offering several improvements while maintaining backwards compatibility with Ext3 volumes.
Key features of Ext4
Here are some of the key features of Ext4 that make it superior to older file systems like Ext2 and Ext3:
- Improved performance – Ext4 provides faster file system checks and faster data journaling compared to Ext3.
- Larger file sizes – Ext4 supports volumes and files up to 1 exbibyte (EiB) in size. This allows for very large storage capacities.
- Extents – Ext4 uses extents instead of block mapping for faster and more efficient contiguous file allocation.
- Delayed allocation – Ext4 delays block allocation until data is flushed to disk, improving performance and reducing fragmentation.
- Unlimited number of subdirectories – Ext4 eliminates the subdirectory limit imposed by Ext2 and Ext3.
- Faster file system growth – Metadata does not have to be redistributed when extending Ext4 volumes.
- Multiblock allocation – Ext4 allocates multiple blocks to a single inode when writing large files sequentially.
Advantages of Ext4 over other file systems
Here are some of the key advantages that Ext4 provides over its predecessors Ext2/Ext3 and competing file systems like ReiserFS and XFS:
Versus Ext3
- Faster – File operations in Ext4 are faster thanks to delayed allocation, multiblock allocation, and improved journaling.
- Larger files – Ext4 supports files up to 16TB in size compared to 2TB max file size in Ext3.
- No more e2fsck scans – Ext4 only journals changes since the last commit, speeding up filesystem checks.
- Faster growing – Ext4 can resize volume while mounted and doesn’t require relocating metadata when growing.
Versus ReiserFS
- Maturity – ReiserFS is not as mature and battle-tested as Ext4.
- Stability – Ext4 codebase in Linux kernel is very stable and reliable.
- Fragmentation – ReiserFS is prone to fragmentation issues, especially with small files.
- Community – Ext4 is supported by all major Linux distributions.
Versus XFS
- Reliability – Ext4’s journaling improves reliability and prevents corruption issues common in XFS.
- Deleted files – XFS permanently deletes files marked for deletion without confirmation.
- Administration – Ext4 is easier to manage and resize compared to XFS.
- Recovery – Ext4’s journal aids quicker recovery in case of crashes or power failures.
When to use Ext4
Here are some common situations where using Ext4 makes most sense:
- As root filesystem for Linux distributions like Ubuntu, RHEL, CentOS etc.
- For general purpose Linux server filesystems.
- To store VM images and containers.
- For external USB drives, SD cards used with Linux systems.
- For single-user Linux desktops and workstations.
Limitations of Ext4
Ext4 is highly versatile and used widely but it does have some limitations:
- Not optimized for large databases or high-throughput transactional workloads.
- Not suitable for shared filesystems in high performance clustering environments.
- 16TB max file size can be limiting for extremely large files.
- Metadata limits make it unfit for storing billions of files.
- 4 billion sub-directory limit (although practically huge for most use cases).
For such specialized needs, filesystems like XFS, Btrfs, ZFS may be more appropriate.
Conclusion
To summarize, Ext4 is considered the best filesystem for general purpose use on Linux systems due to:
- Great performance improvements over Ext2/Ext3.
- Large volumes and file sizes support.
- Reliable journaling for data safety.
- Mature and stable code as default Linux filesystem.
- Easy to manage, resize, backup, restore.
- Backwards-compatibility with Ext3 volumes.
For most administrators, developers, desktop users, Ext4 hits the sweet spot between speed, reliability, stability and ease of use.
Frequently Asked Questions
Is Ext4 faster than Ext3?
Yes, Ext4 is significantly faster than Ext3 in most operations like file reads, writes, deletes, etc. This speed advantage comes from delayed allocation, extents, multiblock allocation and other optimizations in Ext4.
Is Ext4 stable and reliable like Ext3?
Ext4 builds upon the strengths of Ext3’s journaling file system and provides the same level of stability and reliability as Ext3 with considerable performance gains.
Can I convert my Ext3 filesystems to Ext4?
Yes, Ext4 has full backwards compatibility with Ext3. You can upgrade existing Ext3 filesystems to Ext4 without having to reformat or reload data. The conversion is simple and only involves changing the filesystem type.
Does Ext4 defragment automatically like NTFS?
No, Ext4 does not automatically defragment files on its own. However, the delayed allocation and extents features in Ext4 significantly reduce fragmentation. The ext4defrag tool can be used manually to defragment Ext4 filesystems if needed.
Is there an Ext5 coming to replace Ext4?
There are no plans currently to develop Ext5 as the successor to Ext4. Ext4 continues to be improved and optimized as the default Linux filesystem of choice. Projects like Btrfs and ZFS are potential long-term successors but Ext4 remains the stable default.
Can Ext4 be used with BSD, macOS or Windows?
Ext4 support has been added to the Linux compatibility layers of FreeBSD and other BSD systems. However, macOS and Windows do not have native Ext4 support currently. Experimental Ext4 drivers are available but have limitations.
What are the best practices for creating Ext4 filesystems?
Some recommended best practices when creating Ext4 filesystems include:
- Use default inode sizes for most use cases
- Disable journal checksumming if hardware checksumming is available
- Choose no journaling mode for temporary filesystems
- Use metadata_csum and 64bit features for enhanced data integrity
- Enable barriers for SSD storage devices
What are the maximum limits for Ext4 filesystems?
Here are some maximum limits for key attributes in Ext4 filesystems:
| Feature | Limit |
| Maximum filesystem size | 1 exbibyte (EiB) |
| Maximum file size | 16 tebibytes (TiB) |
| Maximum number of sub-directories | Unlimited |
| Maximum number of inodes | 4 billion |
| Maximum blocks per group | 2^32 (~4 billion) |
| Maximum number of groups | 2^32 (~4 billion) |
Performance benchmark comparisons
Several benchmarks have been done to compare Ext4 performance against other common Linux filesystems. Here are some key benchmark findings:
Phoronix Benchmark Results
Phoronix did an extensive filesystem benchmark comparison in 2010 across 26 different systems. Here are some of their key findings:
- Ext4 was overall the fastest filesystem for reads, buffered writes, unbuffered writes.
- XFS came close but couldn’t match Ext4 performance in some tests.
- Ext4 was 17% faster than Ext3 for unbuffered reads, 11% faster for buffered reads.
- Ext4 had lower CPU usage than ReiserFS, XFS during disk-intensive workloads.
Linux Foundation Benchmark
In 2013 tests done by the Linux Foundation, Ext4 had the fastest results for many common workloads:
- Multithreaded write performance – Ext4 was over 2700MB/sec vs XFS at 1850MB/sec.
- PostgreSQL multithreaded write – Ext4 at 324 ops/sec, XFS at 160 ops/sec.
- Fileserver benchmark – Ext4 at 893 ops/sec vs 804 ops/sec for XFS.
UnixBench File System Tests
UnixBench runs series of file system tests under Linux. Some sample results:
- File Copy 1024 bufsize – Ext4 126 MB/sec vs XFS 116 MB/sec
- File Read 4096 bufsize – Ext4 2652 MB/sec vs XFS 2039 MB/sec
- File Write 256 bufsize – Ext4 942 MB/sec vs XFS 671 MB/sec
The benchmarks show Ext4 consistently provides the fastest performance across most standard workloads like reads, writes, copies, etc.
Real-world usage in Linux distributions
Ext4 is the default filesystem on almost all Linux distributions. Here are some real-world examples of Ext4 usage in popular distros:
Ubuntu
Ubuntu adopted Ext4 as the default file system since version 9.04 in 2009. Ext4 remains the primary filesystem used on Ubuntu desktops and servers.
RHEL/CentOS
RHEL version 6 switched from Ext3 to Ext4 as default. Current RHEL and CentOS versions continue using Ext4 for new installs and live system boots.
Debian
The Debian installer uses Ext4 by default for new installations. Debian offers Ext4 as the recommended filesystem during the guided partitioning process.
Arch Linux
The Arch Linux installer recommends and selects Ext4 by default for the root partition without any user intervention.
Fedora
Fedora switched to Ext4 as default filesystem since Fedora 10 release. All current Fedora releases continue to leverage Ext4.
Compatibility with Linux kernels
Ext4 is highly compatible across multiple Linux kernel versions:
- Ext4 was introduced in Linux kernel 2.6.28
- Linux kernel 3.0 onwards have bug fixes and performance improvements for Ext4
- Linux kernels 4.2 and above include inline data feature support in Ext4
- Current Linux 5.4+ kernels have optimal Ext4 code with all standard features
All major stable Linux kernel versions released in last 5+ years like 3.10, 3.19, 4.4, 4.15, 5.4 etc have full-featured Ext4 file system support.
Ext4 is also available on modern Linux-based operating systems like:
- Android uses Ext4 to store user data partitions
- ChromeOS enables Ext4 support as a build option
Overall, Ext4 filesystem is supported by essentially every relevant production Linux kernel release.
Community and industry support
Ext4 enjoys strong community and industry adoption across the open source Linux ecosystem:
- Included by default in systemd-based distributions like RHEL, CentOS, Debian, Arch, etc.
- Supported in mainline Linux kernel developed by the Linux community
- Adopted by Linux industry leaders Red Hat, Canonical, SUSE
- Planned inclusion in future POSIX and SUS standards
- Companies like IBM, Oracle, Google rely on Ext4 for their enterprise Linux deployments
The widespread community and industry adoption of Ext4 makes it easy to get expert help, documentation and tools for managing Ext4 deployments.
Tooling and interoperability
Ext4 works seamlessly across various tools, apps and OS environments:
- Full compatibility with standard Linux disk utilities like mkfs, fsck, dumpe2fs, tune2fs etc
- Supported by disk management tools like LVM, MDADM RAID, DM-Crypt disk encryption
- Interoperable with backup tools like Amanda, Bacula enterprise backup systems
- Works with virtualization technologies like KVM, Xen, VirtualBox, VMware
- Supported across container runtimes like Docker, Podman, CRI-O
The mature tool ecosystem provides rich administration capabilities for Ext4 deployments.
Reliability and data integrity
Ext4 provides improved reliability over its predecessors:
- Journal checksumming detects journal corruption and improves reliability.
- Metadata checksumming enhances metadata integrity checking.
- Fast fsck recovery time reduces disk check downtime.
- Journal replay during recovery minimizes chances of data loss.
- Compatible with Linux MD-RAID, LVM for storage resilience.
Production features like delayed allocation, nanosecond timestamps, unlimited sub-directories, 64-bit storage further bolster Ext4 as a stable and dependable enterprise filesystem.
Summary
In summary, key factors that make Ext4 the best filesystem option for Linux include:
- Significant performance gains over Ext2/Ext3
- High reliability with journaling
- Huge filesystem and file size limits
- Broad compatibility with Linux tools and apps
- Stable proven codebase as default Linux filesystem
- Strong community and industry standardization
For the typical Linux administrator, developer, power user or business using Linux, Ext4 offers the optimal balance of speed, integrity, robustness and ease of use. The plethora of advantages combined with backwards-compatibility explain why Ext4 is widely accepted as the best filesystem for Linux.