1. Prepared by: Assistant prof. Aslamzai
Virtualization
Prepared by: Assistant prof. Aslamzai

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

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

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.

5. Cont..
Before virtualization

6. Cont.…
After Virtualization

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:
memory
processors
storage
network

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.

9. Cont..

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.

11. Cont.
Memory virtualization

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).

13. Cont.
Storage virtualization

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.

15. Cont.
Network virtualization

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.

17. Cont.
Data virtualization

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.

19. Cont.
Application virtualization

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)

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

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

23. Cont.

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

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

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

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.

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

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.

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

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.

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.

33. Cont.
Hardware assisted virtualization

34. Summary of three types of virtualization

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.

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.

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.

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

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 /2012.

40. Native or bare-metal hypervisors

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

42. hosted hypervisors

43. Cont.

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. 
Understand the Difference between ESX and ESXi

45. ESX Understand the Difference between ESX and ESXi

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.
Understand the Difference between ESX and ESXi

47. ESXi Understand the Difference between ESX and ESXi

48. Techniques of VMware VMotion Storage VMotion High Availability
Memory Reclamation

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.
VMware VMotion

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.
VMware Storage VMotion

51. High Availability (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
VMware High Availability

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.

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.

55. Thanks