C-Scan Scheduling

Duration: 4 min

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Inside: a video lesson and guided study material.

Module outline

  1. Quantitative Ability: Percentage, Profit and Loss, Ratio and Proportion (Ratios), Average, Time and Work, Speed Time and Distance, Simple Interest and Compound Interest, Age Problems, Number System, Divisibility Rules, HCF LCM, Algebra, Permutation and Combination, Probability, Data Interpretation, Logarithm, Sequence and Series (Series), Powers and Exponents (Surds and Indices), Speed Mathematics and Basic Mathematics
  2. Logical Reasoning: Seating Arrangements, Puzzle Solving (Puzzles), Data Arrangement, Coding Decoding, Blood Relations, Directions (Direction Test), Ranking, Order and Sequence, Data Sufficiency, Venn Diagram, Inequality, Series (Number and Letter Series) (Numerical Relations and Reasoning), Logical Sequence Of Words, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Selection Decision Table (Decision Making), Analogy, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning)
  3. Verbal Ability: Comprehension / Reading Comprehension / Unseen Passages (Critical Reasoning) (Paragraph Questions), Subject Verb Agreement (Verb Noun Agreement), Tenses, Articles, Preposition, Conjunction, Modals, Active Passive Voice (Voice), Direct and Indirect Speech, Vocabulary, Sentence Re-arrangements (Para Jumbles) (Narrative Sequencing), Sentence Completion (Fill in the blanks), Sentence Correction (Error Correction), Cloze Test (Cloze Passage), Facts, Inference and Judgements
  4. Programming Fundamentals (Technical): C Fundamentals
  5. Data Structures (Technical): Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing
  6. Algorithms (Technical): Algorithm Analysis, Sorting Algorithms, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos, Time Complexity Analysis, Advanced Algorithms
  7. OOPs (Technical): Object Oriented Programming (OOPS)
  8. DBMS (Technical): Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, File Organization & Indexing, Relational Algebra, Relational Calculus, Transaction Management, Concurrency Control, Database Recovery, ORDBMS, Database Security & Authorization, Query Processing & Optimization, Enhanced Data Models, Data Warehousing & Mining, Big Data Systems, NoSQL
  9. SQL (Technical): SQL
  10. Operating Systems (Technical): Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Deadlock, Threads & Process Creation, Memory Management, Virtual Memory, Disc Scheduling, File Management, Windows OS, Linux OS, Security, Distributed Systems, Virtual Machines
  11. Computer Networks (Technical): 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, Hardware basics, Network Security, Mobile Technology, Cloud Computing and IoT, Cyber and Info Security
  12. Software Engineering (Technical): Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management
  13. Coding/Automata Round: Coding Questions by Yash Sir, C Programming by Yash Sir, Programming in C++, Java, Python for Placements by Yash Sir, Pseudo Codes
  14. Personality / Behavioral Assessment: Behavioral Assessment (Behavioral Competency Profiling) (Psychometric Test)
  15. Writing Assessment: English Writing Ability
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This educational video explains the C-SCAN (Circular-SCAN) disk scheduling algorithm, positioning it as an improvement over the standard SCAN algorithm. The primary goal is to provide a more uniform wait time for disk requests. The instructor explains that, similar to SCAN, the disk head moves from one end of the disk to the other, servicing requests encountered along the way. However, a key distinction is made: when the head reaches the opposite end, it immediately returns to the beginning of the disk without servicing any requests on the return trip. The lecture outlines specific advantages, noting that C-SCAN provides more uniform wait times and better response times compared to SCAN. Conversely, a significant disadvantage is identified: the algorithm requires more seek movements specifically to return the head to the starting position, which can impact overall efficiency.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The session begins with the instructor standing next to a slide titled 'C-SCAN Scheduling'. The slide text defines Circular-scan as a variant of SCAN designed to provide a more uniform wait time. It explicitly states that the head moves from one end to the other, servicing requests, but returns to the beginning without servicing requests on the return trip. The instructor reads and elaborates on the 'Advantages' section, which lists 'Provides more uniform wait time compared to SCAN' and 'Better response time compared to scan'. He also points to the 'Disadvantage' section, highlighting 'More seeks movements in order to reach starting position'. As he speaks, he begins to draw a large circle on the whiteboard to the right, representing the disk.

  2. 2:00 – 3:55 02:00-03:55

    The instructor continues his visual explanation by completing the disk diagram. He draws a horizontal line across the circle to represent the head's path, adding squiggly lines to symbolize pending requests. He explains that the head services these requests as it moves in one direction. Upon reaching the end, he illustrates the 'return trip' where the head jumps back to the start without stopping for requests. He emphasizes that this 'circular' movement ensures that requests near the beginning are not left waiting as long as they might be in a standard SCAN algorithm. He points to the diagram to show the extra distance traveled during the return phase, reinforcing the disadvantage of increased seek movements. He concludes by reiterating that while the wait time is more uniform, the cost is the additional movement required to reset the head.

The lecture connects the theoretical definition of C-SCAN with a practical visual demonstration. By contrasting the head's movement with SCAN, the instructor clarifies why C-SCAN offers uniformity at the cost of extra seeks. The diagram serves as a crucial tool to visualize the 'circular' nature of the algorithm, showing the one-way service path and the non-service return path. This visual aid helps students understand the trade-offs inherent in disk scheduling algorithms.

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