Intro to Virtualization

Question 1

what is virtualization in a general sense

Answer 1

mapping resources, data, and interfaces to the underlying system

Question 2

Characteristics of virtualization (3)

Answer 2

1. Abstraction: simplify the underlying system 2. Replication multiple instances of interfaces and resources 3. Isolation: activities and data of one instance is isolated from another instance

Question 3

Levels of Virtualization

Answer 3

1. Multi-tenancy (application level) 2. Containers (OS Level) 3. VM (Hardware Level)

Question 4

What is multi-tenancy on the application level

Answer 4

an instance of a virtualized application isolated from others.

Question 5

Advantages of Multi-tenancy

Answer 5

efficient resource utilization/strong isolation/SaaS is possible with this

Question 6

Disadvantages of Multi-tenancy

Answer 6

limited flexibility/complexity means harder development/isolation is complex/ single point of failure

Question 7

Security for Multi-tenancy

Answer 7

must have proper isolation/difficult when other components are involved

Question 8

Future of Multi-tenancy

Answer 8

things are cheaper and less complex/isolation can be moved to VM/ no more single point of failure

Question 9

What are containers on the OS level and what are some attributes

Answer 9

single instance of an OS…virtualized user environment…isolated against other environments. Less resource efficient but more flexible for the user

Question 10

What is Docker and some attributes

Answer 10

a popular Linux container management layer. Portable deployment across machines/optimized for applications/automatically build images

Question 11

Challenges with docker

Answer 11

one process per container meaning apps that require multiple processes (like database) will need multiple containers. No persistent storage so containers will need separate file system to access persistent data. Network setup is rigid

Question 12

What is a VM

Answer 12

an isolated and efficient copy of the real machine

Question 13

What is a VMM

Answer 13

software program that enables the creation, management and governance of virtual machines (VM) and manages the operation of a virtualized environment on top of a physical host machine. we call it hypervisor

Question 14

Properties of VMM (3)

Answer 14

1. Equivalence: a program running under VMM Should be identical to it running without VMM. 2. Resource control: VMM has complete control over all hardware resources. 3. Efficiency: majority of instructions executed without VMM intervention

Question 15

Two processor modes

Answer 15

User and supervisor mode

Question 16

Three categories of machine instructions

Answer 16

1. Privileged Instructions: executed normally when run in supervisor mode, traps in user mode. 2. Control sensitive instructions: attempts to change resource parameters or processor mode. 3. Behavior sensitive instructions: effect of execution is dependent on resource parameters

Question 17

Virtualization theorem 1

Answer 17

for any conventional 3rd gen computer, a VMM may be constructed if the set of sensitive instructions for that computer is a subset of the set of privileged instructions.

Question 18

Virtualization theorem 2

Answer 18

a conventional 3rd gen computer is recursively virtualizable if it is a) virtualizable and b) a VMM without any timing dependencies can be constructed for it

Question 19

What is paravirtualization

Answer 19

make guest OS aware of virtualization. replace operations requiring privileged instructions with calls to VMM directly. Guest user code remains unmodified. instead of emulating devices, provide virtual devices through a device driver

Question 20

which privilege level does the kernel run in

Answer 20

ring 0

Question 21

can gues OS run in level 1

Answer 21

yes but has to be modified

Question 22

What level do the VMM and host OS run in

Answer 22

level 0

Question 23

Which levels do the OS services run in

Answer 23

levels 1 and 2

Question 24

Which level do applications run in

Answer 24

level 3 the last level

Question 25

What is Type 1 hypervisor

Answer 25

VM runs in user mode/guest OS in VM thinks it’s running kernel mode/if guest OS calls sensitive instructions, hypervisor will trap and execute the instructions