ICT246: Question1 In this task, You Need to Describe How the Processes are Managed Using the Scheduling Algorithm.: Operating Systems Assignment, SUSS, Singapore

Question 1

In this task, you need to describe how the processes are managed using the scheduling algorithm.

The following table shows the process arrival time and service time for 6 processes:

Part (a)

Sketch the execution pattern of all the processes (in alphabetical order) if round-robin with a time-quanta of 1 is used. (Note: If the processes arrived together, you are to assume that the process with lower alphabet number will take priority)

Part (b) Calculate the turnaround time for the processes (A, B, C, D, E, F) if round-robin with a time-quanta of 1 is used.

Part (c) Explain the key design issue of the round-robin algorithm.

Question 2

In this task, you need to demonstrate the creation and usage of virtual machines using Debian OS.

A pet store chain WonderPet has purchased a server with 10 hard disks (each hard disk has a storage size of 2 TB). The server is installed with Debian OS, and it has an operational life of 3 years.

The requirements for the storage space are stated as follow:

• 5 TB is needed for the marketing department to store various marketing materials to promote the pet store. Redundancy is needed such that no data should be lost.
• 1 TB is needed for each store (total 7 stores) to store pet-related materials. Redundancy is needed such that no data should be lost.
• Temporary storage space for all the staff for fast sharing of non-sensitive information. It is estimated that this space will need 2000 GB in the first year, and it will increase 10% in the second year, and it will grow by 50% (from the second year) in the third year. No redundancy is needed although performance is important.

Note that besides the Debian operating system, which is installed in a hard disk, you will need to use ZFS to implement the rest of the 9 hard disks.

Part (a)

Calculate, explain, and justify how do you plan and utilize the 9 hard disks? Sketch a diagram to help in your explanation. Appropriate RAID systems need to be used.

Part (b)

Install additional hard drives in your Debian virtual machine, and simulate the scenario using ZFS with relevant pools and reservations (For this task, you will need to install another 9 hard disks in your Debian virtual machine).

Demonstrate what you have done with clear explanations and appropriate screen-shots.

Question 3

In this task, you need to implement system security and access control in Linux operating system.

Using Debian OS, write and implement one bash shell script. You are to use the root account to execute the script. The bash shell script should have the following specifications:

Part (a)

• The script will prompt the user to enter a password file (an example of a password file is /etc/password)
• It will check whether the password file exists in the current folder, if the file does not exist, it will prompt the user to enter the file again.
• It will keep asking the user to enter the file again until the user inputs a password file that

exists in the current folder.

• If the file exists, it will proceed to check the content of the file and display the following on the screen:

o number of user accounts (you can assume that the user account is having a shell of /bin/bash)

o username of the user accounts and it’s home folder o the largest user-id among all the user accounts

Part (b)

• While displaying the above on the screen, the script will also record all the information in a log file named ‘monitor.log’ in the current folder
• Before the information is appended to ‘monitor.log’, the current date and time needs to be recorded to the file in the format of DD-MM-YY:HH: mm (e.g. if the current date and time

is 10 Mar 2021 1:30 pm, it should be recorded as 10-03-21:13-30) (note: this should not be displayed on the screen)

• The following should then be changed
• If user [your name] doesn’t exist, it needs to be added. However, if [your name] is an existing user, “[your name] existed” needs to be displayed on the screen.
• The owner of the “monitor.log” file should be [your name], group of the file should be [your name]
• Permissions of the “monitor.log” file should be owner can read and write, the group can read, and others do NOT have any permissions.

Part (c)

Documentation (with appropriate screen-shots and explanations) needs to be produced on the execution of the bash shell script with different conditions (e.g. [your name] existed, [your name] does not exist, etc.). Necessary checking needs to be done (e.g. check that the permissions of the monitor.log have changed, etc.).

Appropriate comments must be added to the script to make it easier to understand