COM1032 Operating Systems - File System Basics

File sharing is fundamental in operating systems, allowing multiple users to reuse files, especially in distributed systems across networks.

Remote File Systems: Enable access to files on different computer systems through networking, utilizing methods like FTP, Distributed File Systems, and the World Wide Web, based on a Client-Server Model.

Allocation Methods:

• Contiguous Allocation: Each file occupies a continuous set of blocks, offering simple implementation and fast read times but suffering from fragmentation and difficulties in adding new files.

• Contiguous Allocation with Extents: Uses sections of contiguous blocks, allocated in different places, linked together.

• Linked Allocation: Allocates non-contiguous blocks using linked lists, avoiding external fragmentation but lacking random access.

• File Allocation Table (FAT): Enhances linked allocation by using a table for random block access but has size limitations.

• Indexed Allocation: Employs an index block to store all indexes for a single file, providing random access but risking data loss if the index block is compromised.

• Linked Scheme: Uses multiple index blocks in a linked list for larger files.

• Multilevel Index: Uses inner and outer index blocks for more efficient random access.

• Combined Scheme (Inode): Uses a disk block (Inode) containing a header, direct blocks, and indirect blocks for efficient indexing.