Contiguous File Allocation

Duration: 9 min

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Inside: a video lesson and guided study material.

Module outline

  1. About Course: About the Course
  2. Section A: General Awareness: Polity, Physics, Biology, Chemistry, Static General Knowledge, History, Geography, Indian Economy, GK- Current Affairs, Evolution of Indian Banking (Banking & Financial Awareness), Environment
  3. Section A: General Intelligence & Reasoning ability: Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Data Sufficiency, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Analytical Reasoning (Counting Figures Reasoning), Blood Relations, Syllogisms, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Seating Arrangements, Directions (Direction Test), Puzzle Solving (Puzzles), Calendar, Clock, Cubes & Dices, Selection Decision Table (Decision Making), Logical Sequence Of Words, Crypt Arithmetic, Venn Diagram, Data Arrangement, Inequality, Analogy, Ranking, Order and Sequence, TCS NQT Advanced Reasoning Ability
  4. Section A: Arithmetical & Numerical Ability: Ratio and Proportion (Ratios), Divisibility Rules, Data Interpretation, Mixture and Alligation, Permutation and Combination, Logarithm, Number System, HCF LCM, Sequence and Series (Series), Speed Time and Distance, Percentage, Average, Profit and Loss, Simple Interest and Compound Interest, Time and Work, Pipe and Cistern, Mensuration and Geometry, Powers and Exponents (Surds and Indices), Algebra, Probability, Mental Ability, Age Problems, Partnership, Statistics, Arithmetic, Speed Mathematics and Basic Mathematics, Miscellaneous
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  6. Section A: Hindi Language & Comprehension: भाषा, लिपि, ध्वनि, वर्ण, अक्षर, स्वर, व्यंजन, मात्रा और संयुक्ताक्षर, वर्तनी, वर्ण-विन्यास, अनुस्वार, अनुनासिक, चंद्रबिंदु और ‘र’ के रूप, शब्द, पद और शब्द-भेद, संज्ञा और सर्वनाम, विशेषण और क्रिया, लिंग, वचन, पुरुष और कारक, काल, वाच्य, वाक्य और वाक्य-भेद, संधि, समास, विलोम शब्द, पर्यायवाची शब्द, सामान्य अशुद्धियाँ, अनेक शब्दों के लिए एक शब्द, मुहावरे और लोकोक्तियाँ, अपठित गद्यांश और अपठित पद्यांश, Multi-Topic Content (Cross-Concept Material), वर्णमाला
  7. Section B: Programming, Data Structures, OOP & Java: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling, Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing, Java, OOPS with C++, Language Design, Intro to Compilers, Visual Basics, Syntax Analysis: Bottom-Up, Object Oriented Technology
  8. Section B: Computer Networks, TCP/IP & Network Security: Introduction to CN, Data Communication, DLL: Flow Control, DLL: Access Control, DLL: Error Control, Data Link Layer - Ethernet, Net Layer: IPv4 & Proto, Net Layer: IP Addressing, Transport Layer Services, TL: Congestion & UDP, Application Layer, Hardware basics, Network Access Technologies, Network Security, Society, Law & Ethics, Mobile Computing, Net Layer:Routing Protocol, Cyber Safety and Security
  9. Section B: Teaching Methodology: Child Development, Concept of Pedagogy, Theories, Inclusive Education, Experiential Pedagogy, Assessment & Evaluation, Curriculum Framework & Reforms, National Education Policy (NEP) 2020, Psychology, Teaching-Learning Process, Personality Development, Teaching Methods & Strategies, Learning and Motivation, Learners & Learning Process, Factors Affecting Teaching, Methods of Teaching, Nature, Objectives & Characteristics of Teaching, Teaching-Learning Aids & ICT Integration, Classroom Management & Communication, Evaluation, Assessment & Measurement, Curriculum & School Environment, Inclusive Education & Special Needs, Professional Development & Ethics
  10. Section B: Digital Electronics / Boolean Logic: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Number System, Number Representation, Analog-Digital Conversion
  11. Section B: Operating Systems & Linux: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Threads & Process Creation, Deadlock, Memory Management, Virtual Memory, File Management, Disc Scheduling, Unix OS, Linux OS, Distributed Systems, Windows OS
  12. Section B: Data Base Management System: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, Relational Algebra, SQL, File Organization & Indexing, Transaction Management, Concurrency Control, Database Security & Authorization, Database Recovery, Data Warehousing & Mining
  13. Section B: Internet & Web Technologies: Website, Browser & Services, Internet Fundamentals, Web Design & Development, Protocols & Services, Web Publishing & Hosting, Server Side & Security, HTML Basics, CSS, Emerging Technologies, JavaScript-Basics, .Net Programming, Electronic Data Interchange and E-Commerce, XML
  14. Section B: Computer Fundamentals, IT Basics & Architecture: Basics of COA, Cache Memory Organization, Input Output Organisation, Register Transfer and Microoperations, Control Unit Design, Programming the Basic Computer, Terms & Abbreviations, MS Office Applications, Instr Formats & Modes, Floating Point Rep
  15. Section B: Python Language: Introduction to Python, Tokens, Variables, Data Types, I/O, Operators & Expressions, Control Flow & Looping, Collections & Strings, Functions & Modules, File Handling & Data Analysis
  16. Section B: Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management, extras, Fundamentals of Systems and Information Systems
  17. Section B: Design & Analysis of Algorithms: Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos, Advanced Algorithms
  18. Section B: Mathematics: Linear Algebra, Calculus, Trigonometry, Vectors, Set Theory, Functions, Relations, Propositional and Predicate Logic, Research Process Steps, Graph Theory
  19. Section B: Computer Graphics, Multimedia & Mobile Computing: Basics of Computer Graphics, 2-D Geometrical Transforms and Viewing, 3-D Object Representation, Geometric Transformations and Viewing, Multimedia
  20. Section B: Emerging Trends: Emerging Tech Trends, Knowledge Representation, Natural Language Processing
  21. DSSSB Previous Year Paper:
  22. Business Studies and Management: Business Communication, Business Organization and Management, Financial Accounting, Business Economics, Management Information System (MIS), Knowledge Management & New Economy
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.

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