Operating System

A variety of disk-organization techniques, collectively called RAIDs, are commonly used to address the performance and reliability issues. RAIDs stand for?
(i) Reduced array of independent disks
(ii) Redundant array of individual disks
(iii) Reduced array of individual disks
(iv) Redundant array of independent disks

SPOOLING stands for?
(i) Spontaneous Peripheral Operation Online
(ii) Small Peripheral Operation Online
(iii) Simultaneous Peripheral Operation Online
(iv) None of these

Which of the following is a potential result of bad blocks on a disk?
(i) Faster access time
(ii) Increased storage capacity
(iii) Data loss or corruption
(iv) Improved disk scheduling

Which free-space management technique uses a bitmap to indicate free and occupied blocks?

(i) Bit Vector
(ii) Indexing
(iii) Grouping
(iv) Linked List

______ is the time required to move the disk-arm to the desired track.

(i) Seek time
(ii) Rotational Latency
(iii) Access time
(iv) Waiting time

Which of the following is a valid free-space management technique in file systems?
(i) Bit Vector
(ii) File Mapping
(iii) Page Swapping
(iv) Disk Fragmentation

Which disk scheduling algorithm services requests in the order they arrive?

(i) SCAN
(ii) SSTF
(iii) FCFS
(iv) C-SCAN

Describe seek time, rotational latency, random-access time and their relationship in context of magnetic disks by drawing its moving – head mechanism.

Suppose a disk has 100 cylinders, numbered from 0 to 99. At some time the disk arm is at cylinder 50, and there is a queue of disk access requests for cylinders 4, 34, 10, 7, 19, 73, 2, 15, 6 and 20. Assuming that shortest seek-time first (SSTF) is being used for scheduling the disk access. Calculate the total time taken to satisfy all requests if it takes 1 millisecond to move from one cylinder to adjacent one.

Explain the structure of a file system. Discuss the role of directories, metadata, and file control blocks in file management.

Suppose that a disk drive has 5000 cylinders, numbered 0 to 4999. The drive is currently serving a request at cylinder 143, and the previous request was at cylinder 125. The queue of pending request, in FIFO order is:
86, 1470, 913, 1774, 948, 1509, 1022, 1750, 130

Starting from the current head position, applying Shortest-seek-time-first (SSTF) algorithm find what is the total distance (in cylinders) that the disk arm moves to satisfy all the pending requests.

Differentiate between storage media with constant linear velocity (CLV) and constant angular velocity (CAV).

Suppose that a disk drive has 5000 cylinders, numbered 0 to 4999. The drive is currently serving a request at cylinder 2150, and the previous request was at cylinder 1805. The queue of pending requests, in FIFO order, is:
2069; 1212; 2296; 2800; 544; 1618; 356; 1523; 4965; 3681.
Starting from the current head position, what is the total distance (in cylinders) that the disk arm moves to satisfy all the pending requests for FCFS, SCAN and C-SCAN disk-scheduling algorithms? Draw the head movement diagram also.

Explain shortest-seek-time-first (SSTF) disk scheduling.

Why SSTF scheduling tends to favour middle cylinders over the innermost and outer-most cylinders?

Compare and contrast between linked and indexed disk allocation strategies.

Write short notes on: I-Node

Suppose that a disk drive has 5000 cylinders, numbered 0 to 4999. The drive is currently serving a request at cylinder 143, and the previous request was at cylinder 125. The queue of pending request, in FIFO order, is:
86, 1470, 913, 1774, 948, 1509, 1022, 1750, 130
Starting from the current head position, applying Shortest-seek-time-first algorithm find what is the total distance (in cylinders) that the disk arm moves to satisfy all the pending requests.

Write a short note on:

Boot-block and Bad blocks