Chapter 15: File-System Internals: Mounting, Virtual File Systems, and NFS

File-System Internals: Mounting, Virtual File Systems, and NFS begins with the fundamentals of file-system structures, partitions, and volumes, explaining how various file systems coexist and how mounting integrates them into a single namespace. The chapter examines boot procedures, raw versus cooked partitions, and multi-boot loaders, as well as the importance of metadata for file ownership, protection, and permissions in multi-user environments. File sharing is analyzed in both local and distributed contexts, addressing authentication challenges, user and group IDs, and access control. The Virtual File System (VFS) layer is introduced as a unifying interface enabling multiple file-system types, with Linux’s inode, file, superblock, and dentry objects serving as examples. Remote file systems are discussed extensively, including the client–server model, distributed naming services like DNS, NIS, and LDAP, and the handling of network security and authentication via CIFS, NFS, and Active Directory. The chapter explains consistency semantics—UNIX, session, and immutable-shared-files models—before diving into Network File System (NFS) architecture, covering the mount protocol, stateless server design, RPC/XDR communication, caching strategies, and consistency trade-offs. Implementation details such as path-name translation, cascading mounts, failure modes, and recovery strategies illustrate the complexity of maintaining robust file access. By the end, readers understand how file-system internals integrate storage devices, manage user access, and deliver seamless local and networked file operations.