Filesystems are a critical component of any operating system, as they manage how data is stored and retrieved on storage devices. Choosing the right filesystem can impact performance, reliability, scalability and features. Ext4 and XFS are two of the most popular Linux filesystems, each with their own strengths and weaknesses.
Ext4 is an evolution of the Ext3 filesystem, which itself was derived from Ext2. As a journaling filesystem, Ext4 provides reliability by tracking filesystem changes in a journal prior to committing them to the main filesystem structure. Ext4 includes performance enhancements for flash storage and large files, as well as extensibility features such as extents and preallocation.
XFS was designed by Silicon Graphics in the early 1990s for high performance I/O operations. It utilizes allocation groups and extent-based metadata to optimize large file performance and parallel I/O throughput. XFS offers robust metadata journaling, making it reliable for large storage deployments. Its focus has traditionally been large SANs and high performance computing use cases.
Understanding the key differences between these mature, production-ready filesystems can help administrators select the right solution for their workload requirements.
History and Origins
Ext4 was originally created in late 2006 by a team of developers at Cluster File Systems to address limitations in the ext3 file system for their Lustre parallel distributed file system. The ext4 file system was designed for improved performance, reliability and scaling over ext3, with major improvements including extents, nanosecond timestamps, and delayed allocation.1
XFS was originally developed in the early 1990s by Silicon Graphics for their IRIX operating system. It was designed for high performance and large filesystems (up to exabytes), with major features like B+ tree directory indexes,allocation groups, metadata journaling, and delayed allocation. Key developers behind XFS included Silicon Graphics founders Jim McCoy and Kurt Akey.2
While ext4 improved upon ext3 for modern Linux kernels, XFS was designed from the ground up for performance, especially with extremely large filesystems and high levels of concurrent access. Both were created to address needs around reliability, scalability and performance compared to earlier filesystem options.
Key Technical Differences
Ext4 and XFS have some key technical differences in their underlying structure, metadata handling, and performance optimizations that make each file system better suited for certain use cases.
Ext4 uses extent-based block mapping for storing files, while XFS uses B+ trees for allocating storage space. This gives XFS greater flexibility in allocating large contiguous blocks of storage, making it more efficient for large files and volumes 1.
Both file systems use journaling to provide rapid crash recovery. Ext4 uses a single journal while XFS uses separate journals for metadata and data. This allows XFS to optimize metadata-heavy workloads better than Ext4 2.
For small files, Ext4 shows better performance due to delayed allocation and faster indexing. XFS is optimized for high throughput of large files with features like B+ tree allocation, parallel IO, and preallocation 1.
Performance Benchmarks
When it comes to speed, Ext4 and XFS each have advantages depending on the workload. Here are some key performance differences:
For single-threaded, metadata heavy workloads involving many small files, Ext4 is generally faster. The extent-based metadata structure in Ext4 optimizes it for this type of workload.1
For highly parallel, large file workloads like video editing or scientific computing, XFS excels due to its design for scalability. XFS utilizes allocation groups to optimize parallel throughput.1
In real-world tests, XFS demonstrates higher throughput for sequential reads/writes while Ext4 edges out XFS for randomized workloads involving many small files. However, both Ext4 and XFS offer excellent performance that will likely satisfy most use cases.
When optimally configured, both file systems are capable of reaching over 1GB/sec for sequential I/O on high speed storage. The performance differences mainly emerge in suboptimal setups or specialized workloads.
Reliability and Data Integrity
Both Ext4 and XFS aim to provide robust file systems that prevent corruption. However, they take slightly different approaches.
Ext4 builds on the ext3 file system and includes improvements for reliability like delayed allocation, faster filesystem checking, and persistent preallocation. These help prevent corruption scenarios like unexpected crashes during write operations. Ext4 also uses checksums to detect corruption and has builtin journaling to aid recovery (Storage Tutorials).
On the other hand, XFS utilizes B+ tree indexing and journaling techniques focused on high performance I/O while still maintaining reliability. The XFS designers prioritized preventing crashes rather than optimizing crash recovery. Features like metadata journaling and copy-on-write help maintain integrity through crashes (Reddit).
In real world usage, both file systems demonstrate excellent resilience to crashes with very low rates of corruption. For most general purpose use cases, the differences are minor. However, Ext4 may have a slight edge for data integrity critical scenarios.
Scalability
When it comes to maximum supported file and filesystem sizes, Ext4 has some advantages over XFS. According to Red Hat documentation, Ext4 supports a maximum filesystem size of 16TB and a maximum single file size of 16TB 1. In comparison, XFS file size limits depend on the block size, but maximum filesystem sizes top out at just 100TB 2.
For performance with large datasets, benchmarks tend to give Ext4 a slight edge. Phoronix tested the two filesystems in 2010 with a 450GB database workload and found Ext4 to be faster at writing, sequentially reading, and random reads 3. However, XFS showed better performance for random writes. Overall, Ext4 appears more optimized for large files and datasets.
Feature Set
When it comes to features supported, Ext4 and XFS have some key differences. Ext4 is included in the mainline Linux kernel and has broad support across most Linux distributions. It supports standard filesystem features like permissions, encryption, journaling, and snapshots. Ext4 introduced extents, which helps improve performance for large files by reducing fragmentation. However, Ext4 lacks some more advanced features like native encryption or checksumming.
In contrast, XFS has more robust features geared towards enterprise use cases. XFS supports native encryption for better security. It also utilizes checksumming to detect silent data corruption. Additionally, XFS implements copy-on-write snapshots for easy backup. However, since XFS is not part of the mainline kernel, support for it is less universal across Linux distributions. Specific kernel modules or packages may need to be installed separately.
Overall, for most general purpose Linux deployments, Ext4 provides a good balance of stability and features. But for more demanding storage needs like large media files or database servers, XFS offers optimizations like improved scalability and reliability.
Use Cases
Ext4 and XFS each excel in different use cases depending on the workload. Ext4 is best suited for general purpose use on desktops, laptops, and low-end servers where stability and backwards compatibility are priorities. Its maturity makes it well-suited for most everyday workloads like booting an OS, using office apps, storing photos, etc.
XFS shines for high performance workloads that require I/O speed and parallelization. It was designed for large filesystems with highly concurrent read/write operations such as video editing, 3D modeling, and running databases. XFS performs better than Ext4 for applications that create and delete many small files. It also scales better for managing extremely large files and filesystem sizes.
For database workloads like MySQL, PostgreSQL, and MongoDB, XFS is generally recommended over Ext4 for the performance benefits. However, Ext4 may be preferred if data integrity and reliability are more critical than pure speed. Many web servers and cloud storage providers utilize XFS for its scalability and performance with frequently accessed files.
In summary, Ext4 is best for general purpose use while XFS excels with performance-sensitive applications, especially those involving frequent small file operations and large filesystems.
Adoption and Support
Ext4 is the default file system on some of the most popular Linux distributions, including Ubuntu, Fedora, Debian, and CentOS. Almost all major Linux distributions have adopted Ext4 as the default file system, while XFS remains an option but not the default. Ext4 benefits from its wide adoption in the Linux community and strong backing from most Linux distributions [1].
On the development side, Ext4 is supported by the open-source community and maintained as part of the Linux kernel by developers like Theodore Ts’o. Major backers of Ext4 include Red Hat, SUSE, Canonical, and other leading Linux companies. XFS originated from SGI and later gained support from companies like Red Hat, but lacks the widespread community support of Ext4. For many Linux users and distributions, Ext4 offers a filesystem that is both stable and has strong ongoing development support.
Conclusion
In summary, Ext4 and XFS have some notable differences that make each file system better suited for certain use cases:
Ext4 is based on the tried-and-true Ext3 file system, giving it a longer history and perhaps more stability. It has basic journaling, metadata checksums, and other features focused on data integrity and reliability. Ext4 would be a good choice for general-purpose Linux systems where stability, backwards compatibility, and data integrity are key.
XFS, on the other hand, was designed for performance, supporting large files and file systems up to exabytes in size. It scales better for very large storage arrays and high throughput workloads like video editing or scientific computing. But XFS lacks some of the checksum and integrity features of Ext4. XFS would be optimal for high performance computing use cases where speed is the priority.
For most general purpose Linux servers, Ext4 remains a good default choice. But for specialized applications like high performance computing clusters, big data analytics, or large multimedia storage servers, XFS is likely the better option.
