May 22, 2021 Docker From entry to practice
UnionFS is a layered, lightweight, and high-performance file system that supports modifications to the file system as a layer-by-layer overlay of commits, while simultaneously mounting different directories under the same virtual file system .
The federation file system is the basis of the Docker image. Mirrors can be inherited by layering, and a variety of specific application images can be made based on the underlying image (without a parent mirror).
In addition, different Docker containers can share some of the underlying file system layers, plus their own unique layer of change, greatly improving the efficiency of storage.
The AUFS (AnotherUnionFS) used in Docker is a joint file system. AUFS supports setting read-only,readonly, readwrite, and write-out (whiteout-able) permissions for each member directory (branches like Git), while AUFS has a layered-like concept that logically incrementally modifies branches of read-only permissions (without affecting read-only sections).
The types of joint file systems that Docker currently supports include AUFS, btrfs, vfs, and DeviceMapper.