Basic CS [3i Infotech Placement]: Sample Questions 88 - 90 of 243

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Question 88


Describe in Detail


What is logical volume group?


  • Logical volume group or LVM A relatively new approach to UNIX disks and file systems.
  • Provides abstraction layer between operating system and physical hard drives.
  • Provides a virtual disk space which can be flexibly mapped to real physical disks.
  • The commands in LVM are very similar to the actual physical disks.

Every valid command is preceded by physical volume and volume group as shown below:

  • Physical Volume = pv
  • Volume Group = vg
  • Logical Volume = lv
Physical Volume and Volume Group

Advantages of logical volume group.

  • Offer greater flexibility for disk partitioning.
  • Size of logical volumes can be modified according to need, while the operating system is running
  • Logical volumes can span multiple disks.
  • Disk mirroring is often supported, for greater data reliability

Question 89

Basic CS

Write in Short

Short Answer▾

Hexadecimal equivalent of


Answer is achieved by diving by

Table of Division by 16
Division by QuotientRemainder (decimal)Remainder (hex)Digit


Question 90


Describe in Detail


What are turnaround time and response time?


Response Time and Turnaround Time

Turn Around Time

  • The sum total of waiting time & execution time is known as the turnaround time.
  • The time a given process takes from submission to completion.
  • Example: order of arrival of process P1, P2, P3 was sequential with each taking 5,15, 10 second respetively.
    • First process takes s 5 seconds to finish from submission to completion.
    • Second process takes 5 + 15 = 20, seconds from submission to completion- Add 5 because P2 has waited for P1 to finish.
  • Same, the third process takes 5 + 15 + 10 = 30 seconds from submission to completion.
    • The third process has to wait for both P1 and P2 to finish.
  • The average turnaround time is seconds.
  • We change algorithm from first come first serve to some other scheduling algorithm.
  • We think of the turnaround time as the sum of waiting time and execution time.

Response Time

  • The time from the submission of a request to the time of first response by the CPU.
  • The time difference between the issuance of a command and the start of a response to command.
  • Deceptively similar to waiting time but it is time the given process takes after leaving the ready state until it gets attention of the CPU depending on which scheduling algorithm.
  • Useful in interactive systems for understanding the time between issue of command beginning of the output.
  • In other words, it is time difference between arrival and the first execution.

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