--- sd_hide_title: true --- # 🔎 Overview ```{rubric} EROFS - Enhanced Read-Only File System ``` A modern, flexible, general-purpose, high-performance, block-based immutable filesystem with a highly optimized on-disk format and runtime implementation, designed for a variety of use cases—not just storage space savings—while maintaining optimal runtime performance. [EROFS](https://docs.kernel.org/filesystems/erofs.html) has been formally available since Linux 5.4. It is currently maintained by an open-source community from all over the world, and is still [under active development](roadmap.md). ````{div} sd-d-flex-row ```{button-ref} install :ref-type: doc :color: primary :class: sd-rounded-pill sd-mr-3 Get Started ``` ```{button-ref} faq :ref-type: doc :color: secondary :class: sd-rounded-pill FAQ ``` ```` --- ::::{grid} 1 2 2 3 :gutter: 1 1 1 2 :::{grid-item-card} {octicon}`light-bulb;1.5em;sd-mr-1` Advanced designs :link: design :link-type: doc A modern filesystem more than just another archive format: EROFS is _strictly_ block-aligned to maximize the data utilization of a single disk I/O and enable advanced features like Direct I/O and FSDAX. +++ [Learn more »](design) ::: :::{grid-item-card} {octicon}`gear;1.5em;sd-mr-1` Highly configurable :link: features :link-type: doc Minimal core on-disk format for non-encoded use cases. \ Besides, advanced on-disk and/or runtime features can be enabled on demand. +++ [Learn more »](features) ::: :::{grid-item-card} {octicon}`file-zip;1.5em;sd-mr-1` Compression & Deduplication :link: compression_dedupe :link-type: ref Per-file data compression as an option, normally using fixed-sized output compression to fill up each block. Compressed data can be deduplicated with byte-granularity cut points. +++ [Learn more »](compression_dedupe) ::: :::: --- ```{rubric} Applications ``` - {octicon}`device-mobile;1em` [The Android system firmware](https://source.android.com/docs/core/architecture/kernel/erofs) - {octicon}`container;1em` [Composefs](https://github.com/containers/composefs); [containerd](https://github.com/containerd/containerd/pull/10705); [Dragonfly Nydus](https://nydus.dev/); [gVisor](https://github.com/google/gvisor/pull/9486); [Kata Containers](https://github.com/kata-containers/kata-containers/blob/main/docs/how-to/how-to-use-erofs-snapshotter-with-kata.md); [Kata Containers (rootfs)](https://github.com/kata-containers/kata-containers/blob/main/docs/how-to/how-to-use-erofs-build-rootfs.md); [nerdbox](https://github.com/containerd/nerdbox) - {octicon}`device-desktop` [Archiso](https://gitlab.archlinux.org/archlinux/archiso/-/merge_requests/82); [CoreOS Assembler](https://github.com/coreos/coreos-assembler/pull/4012); [dracut-ng](https://github.com/dracut-ng/dracut-ng/pull/546); [kdump-utils](https://github.com/rhkdump/kdump-utils/pull/33); [KIWI](https://github.com/OSInside/kiwi/issues/2799); [Linglong](https://linglong.dev) - Agent Sandboxes: [Super Rad Company microsandbox](https://github.com/superradcompany/microsandbox); [Tencent Cloud Cube Sandbox](https://github.com/TencentCloud/CubeSandbox) \[[intro (chn)](https://mp.weixin.qq.com/s/AsdIvvZdZMVVCKsi9OG9Gg)\]; [openEuler Conch](https://gitcode.com/openeuler/Conch) \[[intro (chn)](https://mp.weixin.qq.com/s/cpSrWvow71tzlNr6rziOCg)\] - Distributions: [Alpine Linux](https://pkgs.alpinelinux.org/package/edge/community/x86_64/erofs-utils); [Amazon Linux](https://docs.aws.amazon.com/linux/al2023/release-notes/relnotes-2023.7.20250512.html); [Arch Linux](https://archlinux.org/packages/extra/x86_64/erofs-utils); [Azure Linux](https://github.com/microsoft/azurelinux/pull/9971); [Bottlerocket](https://github.com/bottlerocket-os/twoliter/pull/379); [Buildroot](https://buildroot.org); [CentOS Stream](https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/commit/37d0627c30a55e4159f00af2d02b5d64b1dc98e8); [Chromium OS](https://chromium-review.googlesource.com/c/chromiumos/platform/crosutils/+/5125177); [Debian](https://packages.debian.org/sid/erofs-utils); [Deepin Linux](https://github.com/deepin-community/erofs-utils); [Fedora](https://packages.fedoraproject.org/pkgs/erofs-utils/erofs-utils); [Gentoo](https://packages.gentoo.org/packages/sys-fs/erofs-utils); [GNU Guix](https://packages.guix.gnu.org/packages/erofs-utils); [Homebrew](https://formulae.brew.sh/formula/erofs-utils); [MacPorts](https://github.com/macports/macports-ports/pull/28807); [NixOS](https://github.com/NixOS/nixpkgs/tree/nixos-unstable/pkgs/tools/filesystems/erofs-utils); [openAnolis](https://openanolis.cn/?lang=en); [OpenCloudOS](https://gitee.com/OpenCloudOS/OpenCloudOS-Kernel/commit/65fdb18aed207b763076b4014139a57662d999c5); [openEuler](https://gitee.com/openeuler/kernel/pulls/3828); [openSUSE](https://packagehub.suse.com/packages/erofs-utils); [OpenWrt](https://github.com/openwrt/openwrt/pull/19244); [Oracle Linux](https://linux.oracle.com/errata/ELSA-2025-20480.html#:~:text=%5BOrabug%3A%2038042713%5D); [Ubuntu](https://packages.ubuntu.com/erofs-utils); [Red Hat Enterprise Linux](https://access.redhat.com/articles/7084858); [Void Linux](https://github.com/void-linux/void-packages/tree/master/srcpkgs/erofs-utils); [yocto](https://yoctoproject.org); and maybe [more](https://repology.org/project/erofs-utils). - Bootloaders: [Das U-Boot](https://source.denx.de/u-boot/u-boot/-/tree/master/fs/erofs); [GNU GRUB](https://git.savannah.gnu.org/cgit/grub.git/tree/grub-core/fs/erofs.c) ```{rubric} Architecture ``` ![EROFS dataflow in brief](_static/erofs_dataflow.svg) ```{rubric} Feedback & Contributing ``` If you're interested, feel free to send feedback and/or patches to the linux-erofs mailing list <[linux-erofs@lists.ozlabs.org](mailto:linux-erofs@lists.ozlabs.org)> or join our Matrix room <[#erofs:matrix.org](https://matrix.to/#/#erofs:matrix.org)>. [_Developer guides_](developers.md) might be a useful start for newcomers as the first step. Please also take a look at [Code of Conduct](https://www.kernel.org/code-of-conduct.html) for all Linux kernel development communities. ```{rubric} Additional resources ``` [EROFS in-tree documentation](https://www.kernel.org/doc/Documentation/filesystems/erofs.rst) - kernel.org [An introduction to EROFS](https://lwn.net/Articles/934047/) - LWN.net [EROFS: A Compression-friendly Readonly File System for Resource-scarce Devices](https://www.usenix.org/conference/atc19/presentation/gao) - USENIX ATC'19. [EROFS的介绍与讨论](https://mp.weixin.qq.com/s/0_5JnSvfu2pm0CZjBHx8yw) (chn) - Weixin Official Accounts Platform [EROFS Everywhere: An Image-Based Kernel Approach for Various Use Cases](https://youtu.be/nyfECa7OOUM) (chn) with [slides](https://static.sched.com/hosted_files/kccncosschn2023/13/OSS-China-2023-EROFS.pdf) (eng) - [KubeCon + CloudNativeCon + Open Source Summit China 2023](https://www.lfasiallc.com/kubecon-cloudnativecon-open-source-summit-china/) [Finding the Best Block Filesystem for Your Embedded Linux System](https://youtu.be/kLxM4FyiVpQ) - Michael Opdenacker, Bootlin @ EOSS 2023 ```{toctree} :hidden: :caption: 🚀 Get Started install.md mkfs.md features.md casestudies.md ``` ```{toctree} :hidden: :caption: 🚜 For Developers design.md developers.md roadmap.md gsoc.md ``` ```{toctree} :hidden: :caption: 📌 More faq.md credits.md ```