File System Implementation

File System Structure File System Implementation Directory Implementation Allocation Methods Free-Space Management Efficiency and Performance Recovery Log-Structured File Systems NFSFile-System StructureFile structureLogical storage unit Collection of related informationFile system resides on secondary storage (disks). File system organized into layers. File control block – storage structure consisting of information about a file.Operating System Concepts12.1Silberschatz, Galvin and Gagne ©2002Operating System Concepts12.2Silberschatz, Galvin and Gagne ©2002Layered File SystemA Typical File Control BlockOperating System Concepts12.3Silberschatz, Galvin and Gagne ©2002Operating System Concepts12.4Silberschatz, Galvin and Gagne ©2002In-Memory File System StructuresThe following figure illustrates the necessary file system structures provided by the operating systems. Figure 12-3(a) refers...
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File System Implementation Chapter 12: File System Implementation File-System Structure File System Structure File structure File System Implementation Logical storage unit Directory Implementation Collection of related information Allocation Methods File system resides on secondary storage (disks). Free-Space Management File system organized into layers. Efficiency and Performance File control block – storage structure consisting of information about a file. Recovery Log-Structured File Systems NFSOperating System Concepts 12.1 Silberschatz, Galvin and Gagne ©2002 Operating System Concepts 12.2 Silberschatz, Galvin and Gagne ©2002 Layered File System A Typical File Control BlockOperating System Concepts 12.3 Silberschatz, Galvin and Gagne ©2002 Operating System Concepts 12.4 Silberschatz, Galvin and Gagne ©2002 In-Memory File System Structures In-Memory File System Structures The following figure illustrates the necessary file system structures provided by the operating systems. Figure 12-3(a) refers to opening a file. Figure 12-3(b) refers to reading a file.Operating System Concepts 12.5 Silberschatz, Galvin and Gagne ©2002 Operating System Concepts 12.6 Silberschatz, Galvin and Gagne ©2002 11 Virtual File Systems Schematic View of Virtual File System Virtual File Systems (VFS) provide an object-oriented way of implementing file systems. VFS allows the same system call interface (the API) to be used for different types of file systems. The API is to the VFS interface, rather than any specific type of file system.Operating System Concepts 12.7 Silberschatz, Galvin and Gagne ©2002 Operating System Concepts 12.8 Silberschatz, Galvin and Gagne ©2002 Directory Implementation Allocation Methods Linear list of file names with pointer to the data blocks. An allocation method refers to how disk blocks are simple to program allocated for files: time-consuming to execute Contiguous allocation Hash Table – linear list with hash data structure. decreases directory search time Linked allocation collisions – situations where two file names hash to the same location fixed size Indexed allocationOperating System Concepts 12.9 Silberschatz, Galvin and Gagne ©2002 Operating System Concepts 12. ...