Bird
0
0
LLDsystem_design~12 mins

Scheduling algorithm (SCAN, LOOK) in LLD - Architecture Diagram

Choose your learning style9 modes available
LearnWhyDeepArchPracticeChallengeDesignRecallScale
System Overview - Scheduling algorithm (SCAN, LOOK)

This system simulates disk scheduling using SCAN and LOOK algorithms. It manages requests for disk I/O by moving the disk head efficiently to reduce seek time. The key requirement is to optimize the order of servicing requests to minimize disk arm movement.

Architecture Diagram
User
  |
  v
Request Queue
  |
  v
Scheduler (SCAN/LOOK)
  |
  v
Disk Head Controller
  |
  v
Disk Storage
Components
User
client
Generates disk I/O requests
Request Queue
queue
Holds pending disk requests in arrival order
Scheduler (SCAN/LOOK)
service
Orders requests based on SCAN or LOOK algorithm to optimize disk head movement
Disk Head Controller
controller
Moves disk head to requested track positions
Disk Storage
storage
Physical disk where data is read/written
Request Flow - 5 Hops
User → Request Queue
Request Queue → Scheduler (SCAN/LOOK)
Scheduler (SCAN/LOOK) → Disk Head Controller
Disk Head Controller → Disk Storage
Disk Storage → User
Failure Scenario
Component Fails:Scheduler (SCAN/LOOK)
Impact:Disk requests are not ordered efficiently, causing increased seek time and slower disk performance
Mitigation:Fallback to simpler FCFS (First-Come-First-Serve) scheduling or restart scheduler service
Architecture Quiz - 3 Questions
Test your understanding
Which component decides the order of disk requests in SCAN and LOOK algorithms?
AScheduler (SCAN/LOOK)
BRequest Queue
CDisk Head Controller
DDisk Storage
Design Principle
This architecture demonstrates how separating scheduling logic from hardware control improves modularity and allows efficient disk head movement optimization using SCAN and LOOK algorithms.