File-System Structure File-System Implementation Directory Implementation Allocation Methods Free-Space Management Efficiency and Performance Recovery Log-Structured File Systems NFS Example: WAFL File System To describe the details of implementing local file systems and directory structures To describe the implementation of remote file systems To discuss block allocation and free-block algorithms and trade-offs File-System Structure File structure Logical storage unit Collection of related information File system resides on secondary storage (disks) File system organized into layers File control block – storage structure consisting of information about a file.