Linked File Allocation

Duration: 7 min

This video lesson is available to enrolled students.

Return to /learn/RSSB-SENIOR-COMPUTER-INSTRUCTOR/operating-systems/file-management/file-allocation-methods/asset-linked-file-allocation after enrolling

Inside: a video lesson and guided study material.

Module outline

  1. About the Course: About the Course
  2. Paper-1 & 2 | Basic Numeracy: Ratio and Proportion (Ratios), Divisibility Rules, Mixture and Alligation, Permutation and Combination, Logarithm, Number System, HCF LCM, Sequence and Series (Series), Speed Time and Distance, Percentage, Average, Mensuration and Geometry, Age Problems, Arithmetic, Statistics, Probability, Profit and Loss, Simple Interest and Compound Interest, Partnership, Speed Mathematics and Basic Mathematics, Algebra, Powers and Exponents (Surds and Indices), Time and Work, Pipe and Cistern, RSSB Specific Videos - Basic Numeracy
  3. Paper-1 & 2 | Data Interpretation: Data Interpretation
  4. Paper-1 & 2 | General Mental Ability: Mental Ability, RSSB Specific Videos - Mental Ability
  5. Paper-1 & 2 | Logical Reasoning and Analytical Ability: Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Data Sufficiency, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Syllogisms, Seating Arrangements, Blood Relations, Directions (Direction Test), Analytical Reasoning (Counting Figures Reasoning), Puzzle Solving (Puzzles), Calendar, Clock, Cubes & Dices, Venn Diagram, Analogy, Ranking, Order and Sequence, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Data Arrangement, Logical Sequence Of Words, Crypt Arithmetic
  6. Paper-1 & 2 | Decision Making and Problem Solving: Selection Decision Table (Decision Making)
  7. Paper-1 | General Science: Physics, Biology, Chemistry, RSSB Specific Videos
  8. Paper-1 | General Awareness: State Wise GK, GK- Current Affairs
  9. Paper-2 | Fundamentals of Computer: Basics of COA, Number System, Floating Point Rep, Number Representation
  10. Paper - 2 | Digital Logic Systems: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits
  11. Paper-2 | Operating Systems: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Deadlock, Threads & Process Creation, Memory Management, Virtual Memory, Disc Scheduling, File Management, Linux OS, Distributed Systems
  12. Paper-2 | Database Management System: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, Relational Algebra, SQL, Relational Calculus, File Organization & Indexing, Transaction Management, Concurrency Control
  13. Paper-2 | Data Structures: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing
  14. Paper-2 | C Programming: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling
  15. Paper 2 | Oops, C++, Java: Language Design, OOPS with C++, Java, .Net Programming, Java Fundamentals
  16. Paper 2 | Python: Introduction to Python, Tokens, Variables, Data Types, I/O, Operators & Expressions, Control Flow & Looping, Collections & Strings, Functions & Modules, File Handling & Data Analysis
  17. Paper 2 | Emerging Trends and AI: Emerging Tech Trends, Artificial Intelligence
  18. Paper-2 | Algorithms: Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Advanced Algorithms
  19. Paper 2 | Data Communication and Network Security: Introduction to CN, Data Communication, DLL: Access Control, DLL: Flow Control, DLL: Error Control, Data Link Layer - Ethernet, Net Layer: IPv4 & Proto, Net Layer: IP Addressing, Net Layer:Routing Protocol, Transport Layer Services, TL: Congestion & UDP, Application Layer, Hardware basics, Network Security, Ethical Hacking
  20. Paper-2 I Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management
  21. Paper-2 | Computer Organization and Architecture: Cache Memory Organization, Input Output Organisation, Instr Formats & Modes, Control Unit Design, Register Transfer and Microoperations
  22. Paper-2 | Web Development: JavaScript-Basics, HTML Basics, CSS, XML
  23. Pedagogy: Child Development, Concept of Pedagogy, Psychology, Theories, Inclusive Education, Experiential Pedagogy, Curriculum Framework & Reforms, National Education Policy (NEP) 2020
  24. Live Sessions: RSSB Live Sessions
  25. RSSB Paper 1 - Full Mock Tests:
  26. RSSB Paper 2 - Full Mock Tests:
  27. SCI Previous Year Papers:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This lecture introduces Linked Allocation as a file system method that solves the problems associated with contiguous allocation. The instructor explains that with this method, each file is treated as a linked list of disk blocks, which can be scattered anywhere on the physical disk. A key feature is that the directory contains pointers to both the first and last blocks of the file. The video covers the advantages, such as the elimination of external fragmentation and the ability for files to grow dynamically without pre-allocating a fixed size. It also details significant disadvantages, including the overhead of storing pointers, the inability to perform efficient random access, and reliability concerns if a pointer is damaged.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor begins by presenting a slide titled "Linked Allocation" which states that this method solves all problems of contiguous allocation. He explains that with linked allocation, each file is a linked list of disk blocks, and these blocks may be scattered anywhere on the disk. A diagram of a disk cylinder is shown with blocks numbered 0 through 31. The instructor points to a directory entry for a file named "jeep", which has columns for "file", "start", and "end". He traces a path through the blocks (1 -> 6 -> 10 -> 14 -> 18 -> 22 -> 26) to demonstrate how the blocks are linked together. He emphasizes that the directory contains a pointer to the first and last blocks of the file, allowing the system to traverse the entire file. The slide text reads: "The directory contains a pointer to the first and last blocks of the file."

  2. 2:00 – 5:00 02:00-05:00

    The lecture transitions to the advantages of linked allocation. The instructor explains that to create a new file, one simply creates a new entry in the directory. Each directory entry has a pointer to the first disk block of the file. To read a file, the system simply reads blocks by following the pointers from block to block. A major advantage is that the size of a file need not be declared when the file is created; a file can continue to grow as long as free blocks are available. He highlights that there is no external fragmentation with linked allocation, and any free block on the free-space list can be used to satisfy a request. He draws abstract linked list nodes to visualize the structure, reinforcing that blocks are linked sequentially regardless of physical location. The slide text reads: "There is no external fragmentation with linked allocation, and any free block on the free-space list can be used to satisfy a request."

  3. 5:00 – 7:04 05:00-07:04

    The instructor discusses the disadvantages of linked allocation. He notes that to find the i-th block of a file, one must start at the beginning of that file and follow the pointers until reaching the i-th block. Each access to a pointer requires a disk read, which is slow. Another disadvantage is the space required for the pointers, so each file requires slightly more space than it would otherwise. Reliability is also a problem; if a pointer is lost or damaged, the file chain is broken. He suggests partial solutions like using doubly linked lists or storing the file name and relative block number in each block, but notes these schemes require even more overhead. He draws a simple linked list diagram to illustrate the pointer chain. The slide text reads: "Yet another problem is reliability. Recall that the files are linked together by pointers scattered all over the disk, and consider what would happen if a pointer were lost or damaged."

The video provides a comprehensive overview of Linked Allocation in file systems. It begins by defining the concept and illustrating it with a disk diagram and directory structure. The instructor then details the advantages, such as eliminating external fragmentation and allowing dynamic file growth. Finally, he addresses the disadvantages, including slow random access, pointer overhead, and reliability issues, while proposing potential solutions like doubly linked lists. This progression helps students understand the trade-offs involved in file system design.

Loading lesson…