overlayfsbased

Overlayfsbased refers to software, images, or environments that rely on the OverlayFS mechanism in the Linux kernel to create layered file systems. OverlayFS is a union filesystem that merges an upper writable layer with one or more lower read-only layers and presents a single coherent view. In an OverlayFS-based setup, the upperdir holds changes made by the user, while the lowerdir layers remain unchanged. A workdir is required for metadata operations. Deletions are implemented via whiteouts, which indicate that a file from a lower layer should be treated as removed in the merged view.

Common use cases are in container technologies and related tooling. The overlay2 storage driver used by Docker and compatible runtimes, as well as support in Podman and Buildah, rely on OverlayFS to provide efficient layering of base images and writable containers. In these contexts, base images contribute read-only layers, while each container receives a writable layer on top, enabling fast creation, sharing of layers, and space efficiency through copy-on-write semantics.

Limitations and considerations include kernel and filesystem requirements. The underlying filesystems must support OverlayFS features and whiteouts, and some operations may behave differently under OverlayFS compared to other backends. Compatibility can vary with kernel version and distribution defaults; some environments may prefer alternative backends such as AUFS. Performance can be workload-dependent, with benefits from fast layer sharing and potential edge cases in metadata operations.

Overall, Overlayfsbased designs provide lightweight, layer-based file systems suitable for containers, packaging workflows, and other scenarios that benefit from combining multiple read-only layers with a writable layer in a single namespace.