Virtualization. Introduction. Why we interested? 11/28/15. Virtualiza5on provide an abstract environment to run applica5ons.

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1 Virtualization Yifu Rong Introduction Virtualiza5on provide an abstract environment to run applica5ons. Virtualiza5on technologies have a long trail in the history of computer science. Why we interested? Increased performance and compu5ng capacity Underu5lized hardware and sodware resources Lack of space Greening ini5a5ves Rise of administra5ve costs 1

2 Introduction Increased performance and compu/ng capacity. Powerful Enough resources Introduction Underu/lized hardware and so9ware resources. (1) Increased performance and compu5ng capacity (2) The effect of limited or sporadic use of resources Introduction Lack of space. Need addi5onal capacity Cannot afford to build data center 2

3 Introduction Greening ini/a/ves. Data centers are one of the major power consumers We need to reducing the number of servers Introduction Rise of administra/ve costs. Power consump5on and cooling costs Increased demand Servers cannot run on their own Characteristics of virtualized environments Virtualiza5on is a broad concept that refers to the crea5on of a virtual version of something, whether hardware, a sodware environment, storage, or a network. In a virtualized environment there are three major components: guest, host, and virtualiza5on layer. 3

4 The virtualiza5on reference model Characteristics of virtualized environments Example : hardware virtualiza5on the guest is represented by a system image The host is instead represented by the physical hardware Increased security completely transparent manner Guest -> virtual machine -> host VMM Control and filter the ac5vity of guest Preven5ng harmful opera5ons Exposed resources can be hidden by guest 4

5 Managed execution Virtualiza5on of the execu5on environment not only allows increased security, but a wider range of features also can be implemented. In par5cular, sharing, aggrega/on, emula/on, and isola/on are the most relevant features. Managed execution Virtualiza5on of the execu5on environment not only allows increased security, but a wider range of features also can be implemented. In par5cular, sharing, aggrega/on, emula/on, and isola/on are the most relevant features. Portability Example: Hardware virtualiza5on The guest is packaged into a virtual image Easily to display in different computers Example: Programming-level virtualiza5on jars or assemblies can be run without any recompila5on 5

6 Taxonomy of virtualization techniques Taxonomy of virtualization techniques Execution virtualization--introduce Aim to emulate an execu5on environment All these techniques concentrate on providing support for the execu5on of programs Execu5on virtualiza5on can be implemented directly on top of the hardware 6

7 Machine reference model Machine reference model Hardware-level virtualization Hardware virtualiza5on reference model 7

8 Hypervisors Two types of hypervisors Hosted (led) and na5ve (right) virtual machines Hypervisors Two types of hypervisors Hosted (led) and na5ve (right) virtual machines Hypervisors Three proper5es have to be sa5sfied: Equivalence: A guest running under the control of a virtual machine manager should exhibit the same behavior as when it is executed directly on the physical host. Resource control: The virtual machine manager should be in complete control of virtualized resources. Efficiency: A sta5s5cally dominant frac5on of the machine instruc5ons should be executed without interven5on from the virtual machine manager. 8

9 Hypervisors Determines whether these proper5es are sa5sfied is represented by the layout of the ISA of the host running a virtual machine manager. Three theorems that define the proper5es that hardware instruc/ons need to sa5sfy in order to efficiently support virtualiza5on. THEOREM 3.1 For any conven5onal third-genera5on computer, a VMM may be constructed if the set of sensi5ve instruc5ons for that computer is a subset of the set of privileged instruc5ons. THEOREM 3.2 A conven5onal third-genera5on computer is recursively virtualizable if: It is virtualizable and A VMM without any 5ming dependencies can be constructed for it. THEOREM 3.3 A hybrid VMM may be constructed for any conven5onal thirdgenera5on machine in which the set of user-sensi5ve instruc5ons is a subset of the set of privileged instruc5ons. There is another term of hybrid VMM, hybrid virtual machine (HVM) 9

10 Hardware virtualization techniques Hardware-assisted virtualiza/on This term refers to a scenario in which the hardware provides architectural support for building a virtual machine manager able to run a guest opera5ng system in complete isola5on. Full virtualiza/on Full virtualiza5on refers to the ability to run a program, most likely an opera5ng system, directly on top of a virtual machine and without any modifica5on, as though it were run on the raw hardware. To make this possible, virtual machine managers are required to provide a complete emula5on of the en5re underlying hardware. Hardware virtualization techniques Paravirtualiza/on Not-transparent virtualiza5on solu5on Guests need to be modified. Example: Xen, VMWare, Parallels Par/al virtualiza/on Par5al virtualiza5on provides a par5al emula5on of the underlying hardware, thus not allowing the complete execu5on of the guest opera5ng system in complete isola5on. Par5al virtualiza5on allows many applica5ons to run transparently, but not all the features of the opera5ng system can be supported, as happens with full virtualiza5on. Operating System-level virtualization Create execu5on environments for applica5ons No VMM and virtualiza5on is done within single OS OS kernel allows for mul5ple user space Always be 5me-shared OS Examples of opera5ng system-level virtualiza5ons are FreeBSD Jails, IBM Logical Par55on (LPAR), SolarisZones and Containers, Parallels Virtuozzo Containers, OpenVZ, icore Virtual Accounts, Free Virtual Private Server (FreeVPS), and others. 10

11 Programming language-level virtualization Used to achieve ease of deployment of applica5ons, managed execu5on Consists of a virtual machine execu5ng the byte code of a program Example : Java and it is stack-based virtual machine Provide a uniform execu5on environment across different plakorms Application-level virtualization Provide a run5me environment Compare with hardware-level virtualiza5on Replacement library and VMM is much lighter Example: Wine, Vmware ThinApp Other types of virtualization Storage virtualiza/on Storage virtualiza5on is a system administra5on prac5ce that allows decoupling the physical organiza5on of the hardware from its logical representa5on. Network virtualiza/on Network virtualiza5on combines hardware appliances and specific sodware for the crea5on and management of a virtual network. Desktop virtualiza/on Desktop virtualiza5on abstracts the desktop environment available on a personal computer in order to provide access to it using a client/server approach. 11

12 Pros and cons of virtualization Advantages of virtualiza5on Managed execu/on and isola/on Portability and self-containment More efficient use of resources Disadvantages Performance degrada/on Performance is definitely one of the major concerns in using virtualiza5on technology. For instance, in the case of hardware virtualiza5on, the causes of performance degrada5on can be traced back to the overhead introduced by the following ac5vi5es: 1. Maintaining the status of virtual processors 2. Support of privileged instruc5ons (trap and simulate privileged instruc5ons) 3. Support of paging within VM 4. Console func5ons Virtualiza5on technologies at higher levels also have same problem, such as in the case of programming language virtual machines (Java,.NET, and others). Binary transla5on and interpreta5on can slow down the execu5on of managed applica5ons. Disadvantages Inefficiency and degraded user experience Virtualiza5on can some5me lead to an inefficient use of the host. In par5cular, some of the specific features of the host cannot be exposed by the abstrac5on layer and then become inaccessible. In the case of hardware virtualiza5on, this could happen for device drivers: The virtual machine can some5me simply provide a default graphic card that maps only a subset of the features available in the host. In the case of programming-level virtual machines, some of the features of the underlying opera5ng systems may become inaccessible unless specific libraries are used. 12

13 Disadvantages Security holes and new threats Phishing In the case of hardware virtualiza5on, malicious programs can preload themselves before the opera5ng system and act as a thin virtual machine manager toward it. The opera5ng system is then controlled and can be manipulated to extract sensi5ve informa5on of interest to third par5es. In programming-level virtual machines: Modified versions of the run5me environment can access sensi5ve informa5on or monitor the memory loca5ons u5lized by guest applica5ons while these are executed. VMware vs. Virtual Box Cost Performance They all support win 2000,XP,2003, Vista Linux and Mac, but VB is only sodware supports win 7, 2008, FreeBSD Some difference between VirtualBox and VMware are show: hlp:// Thank you 13