--- title: "File system layout; i-node vs linked list" subject: "Operating System" chapter: 5 key: "semester_6/operating_system:fs-layout-inode-vs-linked-list" source: https://www.bctengineer.com/q/semester_6/operating_system/fs-layout-inode-vs-linked-list site: BCT Engineering --- # File system layout; i-node vs linked list Operating System · Chapter 5: File Systems - Asked in: 2068 Magh, 3+5 marks - Video: [File Allocation Methods: Contiguous, Linked & Indexed Explained!](https://www.youtube.com/watch?v=K-BAelpzNC8) — CodeLucky - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_6/operating_system/fs-layout-inode-vs-linked-list - Whole chapter: https://www.bctengineer.com/md/semester_6/operating_system/chapter-5 ## Question What is file system layout? Compare I-Node with linked list. ## Short answer Disk layout: MBR, partition table, boot block, superblock, free-space bitmap, i-node array, root directory, data area. I-node uses index block for fast random access and reliability; linked list chains blocks with pointers, slow random, pointer overhead, less reliable. ## Answer #### File system layout A **file system layout** is the way the disk is organised to store the file system. A disk is divided into partitions; each partition holds an independent file system. ```text Sector 0 whole disk +-----+-----------+-------------+-------------+ | MBR | Partition | Partition 1 | Partition 2 | | | table | | ... | +-----+-----------+-------------+-------------+ One partition: +------+-------+----------+---------+------+----------------+ | Boot | Super | Free- | I-nodes | Root | Files and | | block| block | space | | dir | directories | | | | mgmt | | | | +------+-------+----------+---------+------+----------------+ ``` - **MBR (Master Boot Record):** sector 0; contains boot code and the partition table with start and end of each partition and the active one. The BIOS reads and runs it, which loads the boot block of the active partition. - **Boot block:** first block of a partition; program that loads the operating system. - **Superblock:** key information about the file system: type (magic number), number of blocks, block size, number of i-nodes, free-block counts. - **Free space management:** bit map or list of free blocks. - **I-nodes:** an array of i-nodes, one per file (attributes and block addresses). - **Root directory:** top of the directory tree. - **Data area:** all the other files and directories. #### I-node versus linked-list allocation An i-node holds a list of the file's block addresses in one place (an index); linked-list allocation chains the blocks with pointers stored in each block. | Point | I-node (indexed) | Linked list | |---|---|---| | Location of block addresses | In the i-node (index block) | In each data block (pointer to next) | | Random access | Fast (find address in index directly) | Slow (follow chain from start) | | Block data size | Full block holds data | Pointer reduces usable data size | | Memory use | Only i-nodes of open files in memory | Nothing (but traversing needs disk reads) | | Reliability | Pointers are in one place; protected | One damaged pointer loses rest of the file | | Large files | Needs indirect blocks | No limit, simple | | Overhead for small files | Whole i-node used | Very little | | Sequential access | Good | Good | Therefore i-nodes support both sequential and direct access efficiently and are used in UNIX/Linux file systems, whereas pure linked lists suit only sequential access. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Which gives fast random access? A. Linked list B. I-node, since the address is looked up directly in the index C. Both equal D. Neither Answer: B. Linked lists must follow the chain from the start. (Key point: Random access) 2. Which is more reliable and why? A. Linked list, as pointers are spread out B. I-node, as pointers are in one protected place; one lost pointer in a linked list loses the rest of file C. Both equal D. Linked list, since no table Answer: B. A single damaged pointer in a linked list breaks the file. (Key point: Reliability) 3. What does the superblock store? A. Boot code B. Key file-system information: type, block count, block size, i-node count C. Partition table D. User files Answer: B. The MBR holds boot code and the partition table; the superblock describes the file system. (Key point: Superblock) ## Related in Operating System - [File system layout, i-node, backup](https://www.bctengineer.com/question.md?key=semester_6%2Foperating_system%3Afs-layout-inode-backup) — Operating System, chapter 5 - [File system layers; linked list vs index](https://www.bctengineer.com/question.md?key=semester_6%2Foperating_system%3Afs-layers-linked-list-vs-index) — Operating System, chapter 5 - [File system layout; interface vs implementation](https://www.bctengineer.com/question.md?key=semester_6%2Foperating_system%3Afs-layout-interface-vs-implementation) — Operating System, chapter 5 - [Linked list file system; block size impact](https://www.bctengineer.com/question.md?key=semester_6%2Foperating_system%3Afs-linked-list-block-size) — Operating System, chapter 5 - [File system layout; free block management](https://www.bctengineer.com/question.md?key=semester_6%2Foperating_system%3Afs-layout-free-blocks) — Operating System, chapter 5 - [File system vs virtual memory; contiguous allocation](https://www.bctengineer.com/question.md?key=semester_6%2Foperating_system%3Afs-vs-virtual-memory-contiguous-tape) — Operating System, chapter 5 ## Related in other subjects - [Insert and delete kth node in doubly linked list](https://www.bctengineer.com/question.md?key=semester_4%2Fdata_structure_and_algorithm%3Adoubly-insert-delete-kth) — Data Structure and Algorithm, chapter 4, asked 2× - [Delete last node of doubly linked list](https://www.bctengineer.com/question.md?key=semester_4%2Fdata_structure_and_algorithm%3Adelete-end-node-doubly) — Data Structure and Algorithm, chapter 4 - [Insert before Kth node in doubly linked list](https://www.bctengineer.com/question.md?key=semester_4%2Fdata_structure_and_algorithm%3Adoubly-insert-before-kth) — Data Structure and Algorithm, chapter 4 - [Delete Kth node from doubly linked list](https://www.bctengineer.com/question.md?key=semester_4%2Fdata_structure_and_algorithm%3Adoubly-delete-kth) — Data Structure and Algorithm, chapter 4