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Lecture Operating System: Chapter 06 - University of Technology

Lecture Operating System: Chapter 06 - File Systems presented Files, Directories, File system implementation, Example file systems. | File Systems Chapter 6 6.1 Files 6.2 Directories 6.3 File system implementation 6.4 Example file systems Long-term Information Storage Must store large amounts of data Information stored must survive the termination of the process using it Multiple processes must be able to access the information concurrently File Naming Typical file extensions. File Structure Three kinds of files byte sequence record sequence tree File Types (a) An executable file (b) An archive File Access Sequential access read all bytes/records from the beginning cannot jump around, could rewind or back up convenient when medium was mag tape Random access bytes/records read in any order essential for data base systems read can be move file marker (seek), then read or read and then move file marker File Attributes Possible file attributes File Operations Create Delete Open Close Read Write Append Seek Get attributes Set Attributes Rename An Example Program Using File System Calls | File Systems Chapter 6 6.1 Files 6.2 Directories 6.3 File system implementation 6.4 Example file systems Long-term Information Storage Must store large amounts of data Information stored must survive the termination of the process using it Multiple processes must be able to access the information concurrently File Naming Typical file extensions. File Structure Three kinds of files byte sequence record sequence tree File Types (a) An executable file (b) An archive File Access Sequential access read all bytes/records from the beginning cannot jump around, could rewind or back up convenient when medium was mag tape Random access bytes/records read in any order essential for data base systems read can be move file marker (seek), then read or read and then move file marker File Attributes Possible file attributes File Operations Create Delete Open Close Read Write Append Seek Get attributes Set Attributes Rename An Example Program Using File System Calls (1/2) An Example Program Using File System Calls (2/2) Memory-Mapped Files (a) Segmented process before mapping files into its address space (b) Process after mapping existing file abc into one segment creating new segment for xyz Directories Single-Level Directory Systems A single level directory system contains 4 files owned by 3 different people, A, B, and C Two-level Directory Systems Letters indicate owners of the directories and files Hierarchical Directory Systems A hierarchical directory system A UNIX directory tree Path Names Directory Operations Create Delete Opendir Closedir Readdir Rename Link Unlink File System Implementation A possible file system layout Implementing Files (1) (a) Contiguous allocation of disk space for 7 files (b) State of the disk after files D and E have been removed Implementing Files (2) Storing a file as a linked list of disk blocks Implementing Files (3) Linked list allocation using a file allocation .