Presentation on theme: "Abbas al Ali 441 Murtadha al Nasser 499 Mohammed al Dokhi 468 Ali Khuder 448 Ammar 463."— Presentation transcript:
Abbas al Ali 441 Murtadha al Nasser 499 Mohammed al Dokhi 468 Ali Khuder 448 Ammar 463
Introduction A files is a logical collection. A file system is collection of file. A file system may also include of a variety other objects that share many of properties of files (such as 1/0) devices.
Directories and name A directory or folder is a file system object that contains other file system objects. Actually, a directory is an object that contains the name of file system objects.
Partitions System partitions and boot partitions are names for partitions or volumes on a hard disk that Windows uses when starting. These technical terms are only important if you have more than one operating system installed on your computer (often called a dual-boot or multi boot configuration).
Directory Structure A collection of nodes containing information about all files
File Types Data Text, binary,… Program Regular files – stores information Directory – stores information about file(s) Device files – represents different devices
File Operations Create Write Read Reposition within file – file seek Delete Truncate Open(Fi) – search the directory structure on disk for entry Fi, and move the content of entry to memory Close (Fi) – move the content of entry Fi in memory to directory structure on disk
Access Methods Sequential Access 1. read next 2. write next 3. reset Direct Access 1. read n 2. write n 3. position to n 4. read next 5. write next n = relative block number
Free-Space Management Bit vector (n blocks) Block number calculation for first free block (number of bits per word) * (number of 0-value words) + offset of first 1 bit