Virtualization in cloud computing

1. Virtualization
Prepared by: Assistant prof. Aslamzai
1

2. Learning Objectives
• Understand the basics of virtualization
• Understand how the different resources such as processors, memory, storage,
and network can be virtualized
• Understand the pros and cons of different approaches to virtualization
• Understand the basics of hypervisor and its security issues
• Understand how cloud computing is different from virtualization
• Understand how cloud computing leverages the virtualization for its different
service models
2

3. Virtualization
• Virtualization is the idea of partitioning or dividing the resources of a single
server into multiple segregated VMs.
• Virtualization is the idea of dividing a single hard ware or software into
multiple system
• Virtualization technology has been proposed and developed over a
relatively long period.
• The earliest use of VMs was by IBM in 1960, intended to leverage
investments in expensive mainframe computers
3

4. Virtualization
• Virtualization refers to the act of creating a virtual (rather than actual)
version of something, including (but not limited to) a virtual computer
hardware platform, operating system (OS), storage device, or computer
network resources.
4

5. Cont..
• Before virtualization
5

6. Cont.…
• After Virtualization
6

7. Virtualization Opportunities
• Virtualization is the process of abstracting the physical resources to the pool of
virtual resources that can be given to any virtual machines (VMs). The different
resources can be virtualized:
1. memory
2. processors
3. storage
4. network
7

8. Processor Virtualization
• Processor virtualization allows the VMs to share the virtual processors that are
abstracted from the physical processors available at the underlying infrastructure.
The virtualization layer abstracts the physical processor to the pool of virtual
processors that is shared by the VMs. The virtualization layer will be normally any
hypervisors.
8

9. Cont..
9

10. Memory Virtualization
• The process of providing a virtual main memory to the VMs is known as memory
virtualization or main memory virtualization.
• In main memory virtualization, the physical main memory is mapped to the virtual
main memory as in the virtual memory concepts in most of the OSs. The main idea of
main memory virtualization is to map the virtual page numbers to the physical page
numbers.
• All the modern x86 processors are supporting main memory virtualization. Main
memory virtualization can also be achieved by using the hypervisor software.
Normally, in the virtualized data centers, the unused main memory of the different
servers will consolidate as a virtual main memory pool and can be given to the VMs.
10

11. Cont.
Memory virtualization
11

12. Storage Virtualization
• Storage virtualization is a form of resource virtualization where multiple physical
storage disks are abstracted as a pool of virtual storage disks to the VMs. Normally,
the virtualized storage will be called a logical storage.
• The other advanced storage virtualization techniques are storage area networks
(SAN) and network-attached storage (NAS).
12

13. Cont.
• Storage virtualization
13

14. Network Virtualization
• Network virtualization is a type of resource virtualization in which the physical
network can be abstracted to create a virtual network. Normally, the physical
network components like router, switch, and Network Interface Card (NIC) will be
controlled by the virtualization software to provide virtual network components.
• The virtual network is a single software-based entity that contains the network
hardware and software resources. Network virtualization can be achieved from
internal network or by combining many external networks.
14

15. Cont.
• Network virtualization
15

16. Data Virtualization
• Data virtualization is the ability to retrieve the data without knowing its type and the
physical location where it is stored. It aggregates the heterogeneous data from the
different sources to a single logical/virtual volume of data.
• This logical data can be accessed from any applications such as web services, E-
commerce applications, web portals, Software as a Service (SaaS) applications, and
mobile application.
• It also ensures the single point access to data by aggregating data from different
sources.
16

17. Cont.
• Data virtualization
17

18. Application Virtualization
• Application virtualization is the enabling technology for SaaS of cloud computing.
• The application virtualization offers the ability to the user to use the application
without the need to install any software or tools in the machine. Normally, the
applications will be developed and hosted in the central server.
• The hosted application will be again virtualized, and the users will be given the
separated/isolated virtual copy to access.
18

19. Cont.
• Application virtualization
19

20. Briefly About Virtualization
• Hypervisor/Virtual Machine
Monitor
• Host Operating System
• Guest Operating System
• Every Virtual Machine is given a
set of virtual hardware.
• Involves many software and
hardware architectural
modifications. (Memory
Management, CPU Management)
20 of
42

21. When would we use virtualization
• Running different operating system in one computer
• To make best use of computer hardware
• Maintaining capability with older system
21

22. Approaches to Virtualization
• There are three different approaches to virtualization. Before discussing them, it is
important to know about protection rings in OSs.
• Protection rings are used to isolate the OS from untrusted user applications.
• The OS can be protected with different privilege levels. In protection
ring architecture, the rings are arranged in hierarchical order from ring 0 to ring 3
22

23. Cont.
23

24. Cont.
There are three types of approaches followed for virtualization:
1. Full virtualization
2. Para virtualization
3. Hardware-assisted virtualization
24

25. 1.Full Virtualization
Full virtualization is a technique in which a complete installation of one
machine is run on another.
• –The result is a system in which all software running on the server is within
a virtual machine
25

26. Type of virtualization cont..
• In a fully virtualized deployment, the software running on the server is
displayed on the clients.
26

27. Type of virtualization cont..
• Virtualization is relevant to cloud computing because it is one of the ways in
which you will access services on the cloud.
• That is, the remote datacenter may be delivering your services in a fully
virtualized format.
27

28. Type of virtualization cont..
• Full virtualization has been successful for several purposes:
• Sharing a computer system among multiple users
• Isolating users from each other and from the control program
28

29. Partial virtualization
• Partial virtualization allows multiple operating systems to run on a single
hardware device at the same time by more efficiently using system
resources, like processors and memory
• Partial virtualization typically runs better than the full virtualization
model.
29

30. Partial virtualization
• In Partial virtualization deployment, many different operating systems can
run simultaneously.
30

31. Hardware-Assisted Virtualization
• In the two previous approaches, there is an additional overhead of binary
translation or modification of guest OS to achieve virtualization.
• But in this approach, hardware vendors itself, like Intel and AMD, offer the support
for virtualization, which eliminates much overhead involved in the binary translation
and guest OS modification.
• Popular hardware vendors like Intel and AMD has given the hardware extension to
their x86-based processor to support virtualization. For example, the Intel releases
its Intel Virtualization Technology (VT-x) and AMD releases its AMD-v to simplify the
virtualization techniques.
31

32. Cont.
• In hardware-assisted virtualization, the VMM has the highest privilege (root privilege)
level even though it is working below ring 0.
• The OS resides at ring 0 and the user application at ring 3. Unlike the other
virtualization approaches, the guest OS and the user applications are having the same
privilege level (nonroot privilege level).
• As discussed earlier, the hardware-assisted virtualization technique removes binary
translation and paravirtualization. Here, the OS requests directly the
hypervisor without any translation.
32

33. Cont.
• Hardware assisted virtualization
33

34. Summary of three types of virtualization
34

35. Benefits
• Virtualization can help companies maximize the value of IT investments,
decreasing the server hardware, energy consumption, and cost and
complexity of managing IT systems while increasing the flexibility of the
overall environment.
35

36. Benefits
• But there are also reduced costs across your organization.
• If you reduce the number of physical servers you use, then you save money
on hardware, cooling, and electricity.
36

37. hypervisor
• A hypervisor, also called a virtual machine manager (VMM), is a program that allows
multiple operating systems to share a single hardware host.
• Each operating system appears to have the host's processor, memory, and other
resources all to itself. However, the hypervisor is actually controlling the host
processor and resources, allocating what is needed to each operating system in turn
and making sure that the guest operating systems (called virtual machines) cannot
disrupt each other.
37

38. What is a hypervisor?
• The virtualization tools or hypervisor is the low level program that allows multiple
operating systems to run concurrently on a single host computer.
• hypervisor has two type:
1.native or bare-metal hypervisors
2.hosted hypervisors
38

39. Native or bare-metal hypervisors
• These hypervisors run directly on the host's hardware to control the
hardware and to manage guest operating systems.
• For this reason, they are sometimes called bare metal hypervisors. A guest
operating system runs as a process on the host.
• Example: Xen Server, VMware ESX/ESXi and Microsoft Hyper-V 2008/2012.
39

40. Native or bare-metal hypervisors
40

41. hosted hypervisors
• These hypervisors run on a conventional operating system just as other
computer programs do.
Type-2 hypervisors abstract guest operating systems from the host operating
system.
• For example: VMware Workstation, VMware Player and Virtual Box
41

42. hosted hypervisors
42

43. Cont.
43

44. ESX & ESXi
• ESX (Elastic Sky X) is the VMware’s enterprise server virtualization platform.
• In ESX, VMkernel is the virtualization kernel which is managed by a console operating
system which is also called as Service console.
• Which is linux based and its main purpose is to provide a Management interface for the
host and lot of management agents and other third party software agents are installed on
the service console to provide the functionalists like hardware management and
monitoring of ESX hypervisor.
44

45. ESX
45

46. ESXi
• ESXi (Elastic sky X Integrated) is also the VMware’s enterprise server virtualization platform.
In ESXi, Service console is removed. All the VMware related agents and third party agents
such as management and monitoring agents can also run directly on the VMkernel. ESXi
uses Direct Console User Interface (DCUI) instead of a service console to perform
management of ESXi server. ESXi installation will happen very quickly as compared to ESX
installation.
46

47. ESXi
47

48. Techniques of VMware
• VMotion
• Storage VMotion
• High Availability
48

49. VMotion
• VMotion allows you to quickly
move an entire running virtual
machine from one host to
another without any downtime
or interruption to the virtual
machine This is also known as a
“hot” or “live” migration.
• The entire state of a virtual
machine is encapsulated and the
VMFS file system allows both the
source and the target ESX host to
access the virtual machine files
concurrently.
49

50. Storage VMotion
• Storage VMotion is a new feature introduced
in ESX 3.5, it allows you to migrate a running
virtual machine and its disk files from one
datastore to another on the same ESX host
• The difference between VMotion and
Storage VMotion is that VMotion simply
moves a virtual machine from one ESX host
to another but keeps the storage location of
the VM the same, Storage VMotion on the
other hand changes the storage location of
the virtual machine while it is running and
moves it to another datastore on the same
ESX host. The virtual machine can be moved
to any datastore on the ESX host which
includes local and shared storage.
50

51. HighAvailability (HA)
• Continuously monitors all hosts in
a cluster and restarts virtual
machines affected by a host failure
on other hosts
• Can also monitor guest OS's for a
failure via a heartbeat and restart
them on the same host in case of a
failure
• Continuously monitors and
chooses the optimal physical
servers within a resource pool on
which to restart virtual machines
51

52. 52

53. Summary
• Virtualization is a widely used technology in the IT industry to increase resource
utilization and ROI. It allows the same physical infrastructure to be shared between
multiple OSs and applications. The other benefits of virtualization include dynamic
data center, green IT support, ease of administration, and improved disaster
recovery. There are three types of approaches used to achieve virtualization, namely
full virtualization, paravirtualization, and hardware-assisted virtualization. Full
virtualization completely abstracts the guest OS from the underlying infrastructure.
Paravirtualization provides partial abstraction of the guest OS from the underlying
infrastructure with slight modification of the guest OS. In hardware-assisted
virtualization, the hardware vendor itself offers the support for virtualization.
Hypervisors are the key drivers in enabling virtualization in large-scale cloud data
centers. There are two types of hypervisors available, namely type 1 or bare metal
hypervisor and type 2 or hosted hypervisors.
53

54. Cont.
• Type 1 hypervisors can directly interact with the underlying infrastructure without
the help of the host OS. Type 2 hypervisors need the host OS to interact with the
underlying infrastructure. Since hypervisors are used as the enabling technology in
virtualized data centers, there are different types of attacks targeted on the
hypervisors to disrupt the servers. Normally, the attacks are performed by malicious
codes to compromise the hypervisors. The attacks may target both the guest OS or
host OS. The attacks can be mitigated by strong guest isolation, frequent updates,
enabling least privilege policies, monitoring tools, etc. Virtualization helps in
creating multitenant cloud environment, where a single instance of the resource can
be shared by multiple users. Cloud computing and virtualization are different. Cloud
computing uses virtualization with utility computing to provide different services
such as IaaS, PaaS, and SaaS.
54

55. Thanks
55