Disk Scheduling: Algorithms and Performance Optimization

Question 1

Which disk scheduling algorithm is best suited to minimize disk access time in a real-time system where timeliness is critical?

Accepted Answer

SCAN with Priority

Answer

First Come First Served (FCFS)

Answer

Shortest Seek Time First (SSTF)

Answer

SCAN

Question 2

Which disk scheduling algorithm prioritizes servicing the request that is closest to the current disk head position?

Accepted Answer

Shortest-Seek-Time-First (SSTF)

Answer

First-Come-First-Served (FCFS)

Answer

Scan

Answer

Circular-Scan

Question 3

In a SCAN algorithm, when the disk head reaches the outermost cylinder, what action does it take?

Accepted Answer

Reverses direction and moves towards the innermost cylinder, servicing requests along the way.

Answer

Waits for a new request to arrive before moving.

Answer

Pauses for a predetermined period of time.

Answer

Returns to the innermost cylinder and starts servicing requests from there.

Question 4

Which of the following aspects of system performance is NOT directly affected by disk scheduling algorithms?

Accepted Answer

Memory utilization

Answer

Average seek time

Answer

Disk utilization

Answer

Data throughput

Question 5

When selecting a disk scheduling algorithm, which of the following factors should NOT be considered?

Accepted Answer

Processor speed

Answer

Workload characteristics

Answer

Disk access patterns

Answer

Number of disk drives

Question 6

In a multiprogramming environment, what is the primary function of a disk scheduler?

Accepted Answer

To allocate disk resources equitably among competing processes

Answer

To minimize file fragmentation

Answer

To prevent data corruption

Answer

To enhance file system performance

Question 7

Which disk scheduling algorithm prioritizes requests closest to the current disk arm position?

Accepted Answer

Shortest Seek Time First (SSTF)

Answer

First-Come First-Served (FCFS)

Answer

Scanning (Elevator) Algorithm (SCAN)

Answer

Circular Scanning (CSCAN)

Question 8

In First-Come First-Served (FCFS) disk scheduling, which request is processed next?

Accepted Answer

The most recently arrived request

Answer

The request closest to the current disk arm position

Answer

The request with the highest priority

Answer

The request with the smallest file size

Question 9

In Scanning (Elevator) Algorithm (SCAN), does the disk arm move in both directions?

Accepted Answer

Yes

Answer

No

Question 10

How do disk scheduling algorithms primarily impact computer systems?

Accepted Answer

System throughput

Answer

Resource utilization

Answer

Memory allocation

Answer

Network latency

Question 11

Which scheduling algorithm prioritizes requests closest to the current disk head position?

Accepted Answer

Shortest Seek Time First (SSTF)

Answer

First-Come First-Served (FCFS)

Answer

SCAN

Answer

Circular SCAN (C-SCAN)

Question 12

When evaluating disk scheduling algorithms, which metric is used to assess performance?

Accepted Answer

Average seek time

Answer

Disk utilization

Answer

Throughput

Answer

Response time

Question 13

What is a potential drawback of the SSTF scheduling algorithm?

Accepted Answer

Risk of request starvation

Answer

High average seek time

Answer

Excessive disk arm movement

Answer

Complex implementation

Question 14

What is the primary purpose of a disk queue in an operating system?

Accepted Answer

Hold pending disk I/O requests

Answer

Classify disk requests based on type

Answer

Reduce disk fragmentation

Answer

Boost overall disk performance

Question 15

What advantage does the cylinder-based approach offer in disk scheduling algorithms?

Accepted Answer

Improved disk utilization

Answer

Reduced seek time

Answer

Increased disk throughput

Answer

Enhanced reliability

Question 16

Anticipatory disk scheduling algorithms provide advantages over non-anticipatory ones. What is a key benefit of using anticipatory scheduling algorithms?

Accepted Answer

Reduced average access time

Answer

Minimized variation in access time

Answer

Increased disk bandwidth

Question 17

Which disk scheduling algorithm prioritizes requests based on their arrival order?

Accepted Answer

First-Come First-Served (FCFS)

Answer

Shortest Seek Time First (SSTF)

Answer

SCAN

Question 18

What is the primary objective of the SSTF disk scheduling algorithm?

Accepted Answer

Minimize seek distance

Answer

Minimize average request time

Answer

Maximize disk throughput

Question 19

Which limitation is NOT associated with the SCAN disk scheduling algorithm?

Accepted Answer

High average waiting time

Answer

Potential starvation of requests at the far end of the disk

Answer

High disk arm movement

Question 20

What is the key difference between FCFS and SCAN scheduling algorithms?

Accepted Answer

SCAN prioritizes requests based on their distance from the disk head, while FCFS does not.

Answer

FCFS is non-preemptive, while SCAN is preemptive.

Answer

FCFS is designed for offline scheduling, while SCAN is designed for online scheduling.

Question 21

Which disk scheduling algorithm is most suitable for an environment with significant disk arm movement overhead?

Accepted Answer

SCAN

Answer

FCFS

Answer

SSTF

Question 22

What is a potential drawback of using the C-SCAN disk scheduling algorithm?

Accepted Answer

Starvation of requests at the far end of the disk

Answer

High average request time

Answer

Low disk utilization

Question 23

What is the primary function of a disk controller?

Accepted Answer

Managing communication between the disk drive and the operating system

Answer

Performing disk caching

Answer

Scheduling disk requests

Question 24

Which disk scheduling algorithm prioritizes requests that are near the current head position?

Accepted Answer

Shortest Seek Time First (SSTF)

Answer

FCFS

Answer

SCAN

Answer

C-SCAN

Question 25

Which factor has no influence on the performance of a disk scheduling algorithm?

Accepted Answer

Processor speed

Answer

Disk seek time

Answer

Number of pending requests

Answer

Disk rotation speed

Question 26

What is the primary purpose of a disk buffer in an operating system?

Accepted Answer

To store frequently used data and minimize disk access

Answer

To manage the allocation of disk space

Answer

To handle disk errors and failures

Answer

To optimize the performance of the CPU

Question 27

What is a key function of a disk cache in an operating system?

Accepted Answer

To store frequently accessed data and reduce disk access

Answer

To manage the allocation of disk space

Answer

To handle disk errors and failures

Answer

To optimize the performance of the CPU

Question 28

How might the advent of solid-state drives (SSDs) influence the design and implementation of disk scheduling algorithms?

Accepted Answer

SSDs could facilitate the development of novel disk scheduling algorithms that were previously impractical.

Answer

SSDs could render disk scheduling algorithms unnecessary.

Answer

SSDs could make current disk scheduling algorithms redundant.

Question 29

Disk scheduling algorithms can prioritize certain tasks. How might this impact fairness for different types of users or programs?

Accepted Answer

Prioritizing system tasks to keep the system stable.

Accepted Answer

Prioritizing user-facing apps to improve user experience.

Accepted Answer

Prioritizing tasks based on how time-sensitive they are.

Answer

Prioritizing tasks solely on user preference, even if it harms the system.

Question 30

Which disk scheduling algorithm processes requests in the order they arrive, without considering their relative position on the disk?

Accepted Answer

FCFS (First Come First Served)

Answer

SSTF (Shortest Seek Time First)

Answer

C-SCAN (Circular SCAN)

Answer

SCAN (Elevator Algorithm)

Question 31

Which of the following is NOT a commonly used metric for evaluating disk scheduling algorithms?

Accepted Answer

Memory usage

Answer

Throughput

Answer

Average seek time

Answer

Disk utilization

Question 32

The SSTF (Shortest Seek Time First) algorithm reduces seek time by:

Accepted Answer

Processing requests with the closest seek distance first

Answer

Using a queue to store requests

Answer

Prioritizing smaller I/O requests

Answer

Keeping track of disk head position

Question 33

The SCAN (Elevator Algorithm) algorithm is particularly suitable for disk access patterns that:

Accepted Answer

Sequentially access large contiguous areas of the disk

Answer

Randomly access different parts of the disk

Answer

Process a mix of read and write requests

Answer

Prioritize high-priority requests

Question 34

C-SCAN (Circular SCAN) differs from SCAN by:

Accepted Answer

Restarting disk head movement from the beginning of the disk after reaching the end

Answer

Moving the disk head only in one direction

Answer

Prioritizing read requests over write requests

Answer

Using multiple disk arms to increase concurrency

Question 35

Non-preemptive scheduling algorithms do NOT allow processes to be interrupted once they start execution. Which of the following is a non-preemptive scheduling algorithm?

Accepted Answer

FCFS (First Come First Served)

Answer

Round-robin

Answer

Priority scheduling

Answer

Shortest remaining time first

Question 36

The Elevator Sort (SCAN) algorithm optimizes disk access time by:

Accepted Answer

Moving the disk head in both directions to service requests

Answer

Prioritizing requests for high-priority files

Answer

Minimizing disk rotation time

Answer

Reducing the number of seek operations

Question 37

Parallel scheduling is an effective technique for maximizing disk performance in systems with:

Accepted Answer

Multiple disk drives

Answer

High-priority requests

Answer

Random access patterns

Answer

Large file sizes

Question 38

Which disk scheduling algorithm gives priority to requests located closest to the current head position, reducing seek time?

Accepted Answer

SSTF (Shortest Seek Time First)

Answer

C-SCAN (Circular SCAN)

Answer

FCFS (First Come First Served)

Answer

SCAN (Elevator Algorithm)

Question 39

In the context of disk performance optimization, which aspect do FCFS, SSTF, and SCAN algorithms primarily address?

Accepted Answer

I/O Scheduling

Answer

File System Management

Answer

Process Management

Answer

Memory Management

Question 40

What fundamental difference distinguishes SCAN from C-SCAN disk scheduling algorithms in terms of their operational behavior?

Accepted Answer

SCAN allows movement in both directions, while C-SCAN restricts movement to one direction.

Answer

SCAN is suitable for movable-head disks, while C-SCAN is for fixed-head disks.

Answer

SCAN is faster than C-SCAN.

Question 41

When evaluating the performance of disk scheduling algorithms, which metric is not typically considered?

Accepted Answer

Bandwidth

Answer

Throughput

Answer

Disk Utilization

Answer

Average Seek Time

Question 42

Identify a potential drawback associated with using the SSTF disk scheduling algorithm.

Accepted Answer

Possible starvation of requests located far from the current head position.

Answer

Low disk utilization.

Answer

High average seek time.

Question 43

In an operating system, what is the primary purpose of a disk scheduler?

Accepted Answer

To determine the order of disk requests to optimize performance.

Answer

To manage file systems.

Answer

To allocate memory space to disk processes.

Question 44

Which disk scheduling algorithm is recognized for its simplicity and fair treatment of requests?

Accepted Answer

FCFS

Answer

SSTF

Answer

C-SCAN

Answer

SCAN

Question 45

What is the primary goal of disk scheduling in an operating system?

Accepted Answer

To minimize seek time and enhance disk performance.

Answer

To maximize disk capacity.

Answer

To prevent disk fragmentation.

Question 46

Within the FCFS disk scheduling algorithm, what is a potential drawback in terms of performance?

Accepted Answer

Increased average seek time due to disregarding head position.

Answer

Elevated CPU consumption.

Answer

Amplified disk fragmentation.

Question 47

What is the fundamental distinction between SCAN and C-SCAN disk scheduling algorithms?

Accepted Answer

C-SCAN prevents starvation by enforcing a fixed direction for head movement.

Answer

C-SCAN sequences requests based on arrival time.

Answer

SCAN optimizes for sequential access while C-SCAN prioritizes random access.

Question 48

The primary objective of disk scheduling algorithms is to:

Accepted Answer

Optimize disk access time by minimizing head movement and seek time.

Answer

Increase disk storage capacity.

Answer

Enhance data transfer rates across networks.

Question 49

Which of the following factors can impact the effectiveness of disk scheduling algorithms?

Accepted Answer

Characteristics of disk head movement and patterns of request arrival.

Answer

Processor speed and memory size.

Answer

Network bandwidth and latency.

Question 50

A disk scheduling algorithm that prioritizes requests based on their arrival time is:

Accepted Answer

First Come First Served (FCFS)

Answer

SCAN

Answer

Shortest Seek Time First (SSTF)

Answer

C-SCAN