structural:expansion, linguistic:paraphrasing
Architecture

A local file system's architecture can be described as layers of abstraction even though a particular file system design may not actually separate the concepts.

The logical file system layer provides relatively high-level access via an application programming interface (API) for file operations including open, close, read and write – delegating operations to lower layers. This layer manages open file table entries and per-process file descriptors. It provides file access, directory operations, security and protection.

The virtual file system, an optional layer, supports multiple concurrent instances of physical file systems, each of which called a file system implementation.

The physical file system layer provides relatively low-level access to a storage device (e.g. disk). It reads and writes data blocks, provides buffering and other memory management and controls placement of blocks in specific locations on the storage medium. This layer uses device drivers or channel I/O to drive the storage device.