🔍 Case Studies

The EROFS filesystem has been deployed in production at large scale since its inclusion in Linux 5.4 and is now part of several prominent open-source ecosystems.

It started in 2017, when Linux image filesystems were still primitive (cramfs and ROMFS), or focused solely on extreme image size reduction (squashfs) for low-end embedded devices, while lacking good real-time response in low memory scenarios. In addition, kernel development for most in-tree immutable filesystems (particularly on-disk format enhancements) was inactive for a decade at that time.

To meet our production performance needs and fill the gap for a better high-performance Linux image filesystem, the EROFS project was launched. Before being successfully upstreamed, it had already been successfully deployed on millions of Android smartphones and it should be billions of various devices now.

Note that the EROFS filesystem aims to be a generic image filesystem from the beginning, not limited to a specific use case (e.g. only for Android system partitions). We believe that even if image filesystems have certain useful use cases, in reality it often fails to attract many real experienced kernel filesystem developers. Designing a specialized filesystem for a single use case will lead to unhealthy development, unnecessary reinvention, and fragmentation.

Currently, apart from the initial Android use cases, we are also focused on bringing up a better image filesystem for containers. Many recent features, such as native layering support, large folios, file-backed mounts, inode-based page cache sharing, and direct access for files, are dedicated to container image use cases.

In several popular projects, EROFS is used as a powerful tool to provide advanced features or improve the de-facto standard Docker/OCI container images, such as ComposeFS and the EROFS containerd snapshotter. However, EROFS can also serve as a next-generation container filesystem on its own. We believe it should be more useful as the EROFS container ecosystem continues to evolve.

The EROFS filesystem is now a completely community-driven, neutral open-source project and part of the Linux kernel. If you’re working on, or interested in image filesystem use cases, feel free to provide feedback and join us.

🚧 Detailed introduction to the current main use cases is still in progress.