Contiguous File Allocation

Duration: 9 min

This video lesson is available to enrolled students.

Return to /learn/BIHAR-STET-COMPUTER-SCIENCE-COMPLETE-COURSE/unit-5-operating-system/file-management/file-allocation-methods/asset-contiguous-file-allocation after enrolling

Inside: a video lesson and guided study material.

Module outline

  1. About the course: About the Course
  2. Mathematical Aptitude: संख्या पद्धति / Number System, महत्तम समापवर्तक और लघुत्तम समापवर्त्य / HCF and LCM, Divisibility Rules, प्रतिशत / Percentage, अनुपात और समानुपात / Ratio and Proportion, औसत / Average, लाभ, हानि और बट्टा / Profit, Loss and Discount, समय और कार्य / Time and Work, घन क्षेत्रमिति / Solid Mensuration, साधारण और चक्रवृद्धि ब्याज / Simple and Compound Interest, समय, चाल और दूरी / Time, Speed and Distance, Age Problems, मिश्रण और एलिगेशन / Mixture and Alligation, Algebra, सरलीकरण, घातांक और करणी / Simplification, Indices and Surds, Pipe and Cistern, Trigonometry, Statistics, आँकड़ा निर्वचन / Data Interpretation, Arithmetic, समुच्चय, संबंध, फलन और विविक्त गणित / Sets, Relations, Functions and Discrete Mathematics, संख्या पद्धति और संख्या सिद्धांत / Number Systems and Number Theory, निर्देशांक ज्यामिति, सदिश और त्रिविमीय ज्यामिति / Coordinate Geometry, Vectors and 3D Geometry, बहुपद, समीकरण और सम्मिश्र संख्याएँ / Polynomials, Equations and Complex Numbers
  3. Logical Reasoning: श्रेणी / Series, कूट लेखन एवं कूट वाचन / Coding-Decoding, सादृश्यता एवं वर्गीकरण / Analogy and Classification, रक्त संबंध / Blood Relations, दिशा एवं दूरी / Direction and Distance, क्रम एवं रैंकिंग / Order and Ranking, अशाब्दिक तर्क / Non-Verbal Reasoning, बैठक व्यवस्था एवं पहेलियाँ / Seating Arrangement and Puzzles, Syllogisms, वेन आरेख, न्याय वाक्य एवं असमानता / Venn Diagrams, Syllogism and Inequalities, गणितीय संक्रियाएँ एवं लुप्त संख्या / Mathematical Operations and Missing Numbers, वर्णमाला एवं संख्या परीक्षण / Alphabet and Number Test, कथन आधारित तार्किक विवेचन / Statement-Based Reasoning, Analytical Reasoning (Counting Figures Reasoning), घन, पासा एवं आकृतियों की गिनती / Cubes, Dice and Figure Counting, कैलेंडर एवं घड़ी / Calendar and Clock, Clock
  4. General Knowledge: वैज्ञानिक उपलब्धियाँ और अनुसंधान / Scientific Achievements and Research, Chemistry, Biology, History, Geography, Polity, Indian Economy, समसामयिकी / Current Affairs, Static General Knowledge
  5. Art of Teaching: शिक्षण-अधिगम प्रक्रिया एवं कक्षा प्रबंधन / Teaching-Learning Process and Classroom Management, Learners & Learning Process, Factors Affecting Teaching, शिक्षण विधियाँ एवं उपागम / Teaching Methods and Approaches, सूक्ष्म शिक्षण एवं कक्षा संप्रेषण / Microteaching and Classroom Communication, शिक्षण सहायक सामग्री एवं शैक्षिक तकनीकी / Teaching Aids and Educational Technology, आकलन एवं मूल्यांकन / Assessment and Evaluation, शिक्षक: गुण, व्यावसायिक नैतिकता एवं विकास / Teacher: Qualities, Professional Ethics and Development, शैक्षिक नीतियाँ, अधिनियम एवं प्रशासन / Educational Policies, Acts and Administration, पाठ्यचर्या, कला एवं सह-शैक्षिक क्षेत्र / Curriculum, Arts and Co-curricular Areas, निर्देशन एवं परामर्श / Guidance and Counselling, दिव्यांग बच्चों की शिक्षा / Education of Children with Disabilities, Micro-Teaching & Teaching Skills, पाठ योजना / Lesson Planning
  6. Environmental Science: Environment
  7. Unit 1 | Digital Electronics: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Number System, Number Representation
  8. Unit 2 | COA: Basics of COA, Floating Point Rep, Cache Memory Organization, Input Output Organisation, Instr Formats & Modes, Control Unit Design, Register Transfer and Microoperations, Programming the Basic Computer
  9. Unit 3 | C Programming: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling
  10. Unit 3 | Data Structures: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing
  11. Unit 4 | Algorithms: Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos, Advanced Algorithms
  12. Unit 5 | Operating System: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Threads & Process Creation, Deadlock, Memory Management, Virtual Memory, Disc Scheduling, File Management
  13. Unit 6 | Database Management System: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, File Organization & Indexing, Relational Algebra, SQL, Transaction Management, Concurrency Control
  14. Unit 7 | Computer Networks: Introduction to CN, Data Communication, DLL: Access Control, DLL: Flow Control, DLL: Error Control, DLL: Framing, Data Link Layer - Ethernet, Net Layer: IPv4 & Proto, Net Layer: IP Addressing, Net Layer:Routing Protocol, Transport Layer Services, TL: Congestion & UDP, Application Layer
  15. Unit 8 | Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management
  16. Unit 9 | Object Oriented Programming: OOPS with C++
  17. Unit 10 | Web Development: HTML Basics, CSS, JavaScript-Basics, XML, Node.js
  18. Unit 11 | Theory Of Computation: Introduction to TOC, Deterministic FA (DFA), Non-Deterministic FA, Regular Expressions, Grammar, Regular Language Properties, Moore & Mealy Machines, Pushdown Automata & CFG, Turing Machines
  19. Unit 12 | IoT: Emerging Tech Trends, Cloud Computing, कंप्यूटर नेटवर्क / Computer Networks
  20. Unit 13 | Artificial Intelligence: Approaches to AI, Search Algorithms, Game Playing, Knowledge Representation, Natural Language Processing, Artificial Neural Networks, Genetic Algorithms
  21. Unit 14 | E-Commerce: Electronic Data Interchange and E-Commerce, Role of Internet and Web Services, Security in Mobile and Wireless Computing, Physical Security and Cryptography Basics, Cyber Safety and Security
  22. Unit 15 | Multimedia: Multimedia
  23. Unit 16 | Python: Introduction to Python, Tokens, Variables, Data Types, I/O, Operators & Expressions, Control Flow & Looping, Collections & Strings, Functions & Modules, File Handling & Data Analysis, DSA using Python
  24. Full Length Mock Tests — General Paper:
  25. Full Length Mock Tests — Computer Science (Paper II):
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This educational video lecture focuses on the concept of Contiguous Allocation within file systems. The instructor begins by defining the core requirement: each file must occupy a set of contiguous blocks on the disk. He explains that disk addresses create a linear ordering, which simplifies access patterns. Using a visual directory table and a disk block diagram, he demonstrates how files are mapped to specific starting blocks and lengths. The lecture then transitions to a critical evaluation of the method, discussing its advantages in terms of access speed and its significant disadvantages related to external fragmentation and file modification constraints. He uses hand gestures to point out specific elements on the slide.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor introduces the topic "Contiguous Allocation" with a slide stating that each file must occupy a set of contiguous blocks on the disk. He explains that disk addresses define a linear ordering, meaning accessing block b+1 after block b normally requires no head movement. He displays a directory table with columns for "file", "start", and "length". He points to the entry for "count", which starts at block 0 with a length of 2, indicating it occupies blocks 0 and 1. He writes "DBA" (Disk Block Address) next to block 0 on the disk diagram to emphasize the starting point. The slide text explicitly mentions "assuming that only one job is accessing the disk". The disk diagram shows blocks numbered sequentially from 0 to 31 in a cylindrical shape. He uses his hand to point at the specific blocks on the diagram. He also points to the "count" label in the directory.

  2. 2:00 – 5:00 02:00-05:00

    The instructor elaborates on the directory table entries to show how different files are allocated. He points to "tr" starting at block 14 with length 3, "mail" starting at 19 with length 6, "list" starting at 28 with length 4, and "f" starting at 6 with length 2. He draws a physical disk platter diagram to visualize how these blocks are arranged on the actual hardware, drawing concentric circles for tracks and lines for sectors. He explains that this linear ordering allows for efficient access patterns. He highlights that because the blocks are contiguous, the disk head does not need to move significantly between blocks of the same file, which improves performance for sequential access. He gestures towards the directory table to reinforce the mapping logic. The "mail" file occupies blocks 19 through 24. He draws lines on the disk diagram to represent the tracks. He also points to the "mail" entry in the directory.

  3. 5:00 – 9:00 05:00-09:00

    The lecture shifts to the pros and cons of this allocation method. A slide lists "Advantage" as easy access supporting both sequential and direct access. The "Disadvantage" section mentions suffering from external fragmentation. The instructor explains that deleting a file leaves a hole, and if a new file is too large for that hole, it cannot be placed there. He discusses the difficulty of file modification; if a file grows larger than its allocated contiguous space, it cannot simply expand. He writes "1KB" and "700B" on the disk diagram, likely illustrating block sizes or file size constraints relative to available space. He concludes that while efficient for access, the fragmentation issue is a significant drawback. The slide text explicitly lists "Suffer from the problem of external fragmentation" and "Another problem with contiguous allocation file modification". A copyright banner "THIS IS COPYRIGHTED CONTENT OF KNOWLEDGEGATE EDUVENTURES" is visible at the bottom. He points to the disadvantage bullet points on the slide. He also writes "1KB" and "700B" on the board.

The video provides a comprehensive overview of contiguous allocation, starting with the fundamental definition of storing files in contiguous blocks. It progresses to practical examples using a directory table and disk diagrams to show how files like "count", "tr", and "mail" are mapped to physical blocks. The instructor then transitions to a critical analysis of the method, highlighting the primary advantage of efficient sequential and direct access due to linear ordering. However, he emphasizes the major disadvantages, specifically external fragmentation and the inability to easily modify file sizes, which limits the flexibility of this allocation method in dynamic file systems. He uses visual aids to clarify complex concepts.

Loading lesson…