Unit 2 - Disks and boot

Question 1

What is a partition and why would we use them?

Answer 1

• A partition is a chunk of the hard disk.

- We may use them to decrease chance of corrupting data.

Question 2

How do we display the partitions of a hard drive?

Answer 2

sfdisk -l /dev/sda

Question 3

What are the minimum partitions?

Answer 3

/ - Main directory tree such as OS files

boot/ - Used to store boot files

swap - Used as virtual memory space

Question 4

What are the optional partitions?

Answer 4

/home - Used to store user files

/var - Used to store system config files that can change.

Question 5

Why is it dangerous to resize partitions?

Answer 5

As most partitions together use 100% of the disk.

Resizing can cause other partitions to be decreased and subsequently cause data loss.

This also damages the partition table.

Question 6

What are some features of LVM regarding partitions?

Answer 6

• It is capable of creating a partition using more then one physical hard drive disk.

Question 7

What command is used to show logical volumes of partitions?

Answer 7

lvdisplay

Question 8

What command is used to create a LV partition?

Answer 8

lvcreate -L -n

Question 9

What command is used to reduce an LV partition?

Answer 9

lvreduce

Question 10

What command is used to extend a partition size by adding more physical space?

Answer 10

vgextend

Question 11

How do you find the id and file type of partitions?

Answer 11

blkid

Question 12

How to see the disk space that is free?

Answer 12

df -h

Question 13

How to see space being used by a disk space?

Answer 13

du -h

Question 14

What command do you use to start a service?

Answer 14

systemctl start

Question 15

What command do you use to make a service start every-time you boot?

Answer 15

systemctl enable

Question 16

What is the difference between systemctl restart and reload?

Answer 16

Restart does Stop and Start

Reload starts a new service with the new config and once it is operating with no errors it stops the old service using the old config to ensure minimal downtime.

Question 17

Explain what init.d is and how its runlevels work?

Answer 17

Init.d is used to run commands used for booting and setting up.

It consists of 7 run levels.

Each runlevel has a softlink to a script which controls a service.

Question 18

What is the syntax of an init.d softlink filename? And how does priority work?

Answer 18

S/K

• The higher the priority means it starts first.

Question 19

How does SystemD approach running system scripts?

Answer 19

It creates a tree of dependency for all the scripts that need to be run.

Question 20

How does XINETD work?

Answer 20

Instead of running all services it runs a socket which listens for messages.

It then runs a service that corresponds to that can deal with the message.