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Advanced Topic 40 of 51 Operating Systems

Disk Scheduling

Ordering disk requests such as SCAN to reduce seek time.

How it works

The disk head scheduler orders requests to minimize seeks: FCFS, SSTF (shortest seek first), SCAN (elevator) and C-SCAN. SSDs need little seek optimization.

Where it is used

HDD I/O performance.

Common pitfall

SSTF can starve distant requests.

Where it fits in the course

Disk Scheduling is topic 40 of 51 in Operating Systems, rated Advanced. It follows Journaling File Systems. The next topic is I/O Management.

Practice and explore

How to study this topic

  1. Read the explanation above and restate the definition in your own words.
  2. Open the interactive lesson and answer its mini quiz.
  3. Read the common pitfall, then write a short example that avoids it.
  4. Check your understanding in the Operating Systems quiz, and revisit the topic if you miss a question.

Frequently asked questions

What is Disk Scheduling?
Ordering disk requests such as SCAN to reduce seek time. It belongs to Operating Systems and is an advanced-level topic.
Where do people use Disk Scheduling?
HDD I/O performance.
What is the most common mistake with Disk Scheduling?
SSTF can starve distant requests.
What should I learn before this topic?
Start with Journaling File Systems, the topic just before it in Operating Systems.
How can I practice it?
Answer the mini quiz in the interactive lesson, then take the Operating Systems quiz.
Is Disk Scheduling hard to learn?
It is an Advanced topic. Expect to read the explanation more than once and to connect it with earlier topics. Working through a small example by hand helps most.
How long does it take to learn Disk Scheduling?
Most learners can read the explanation and finish the interactive lesson in under an hour. Fluency comes from applying the idea, so plan a few short practice sessions with the quiz.
Which topics are related to Disk Scheduling?
Journaling File Systems, I/O Management, File Allocation Methods are closely connected. The full list is in the related topics section of this page.
What should I study after Disk Scheduling?
Continue with I/O Management, the next topic in Operating Systems.

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