Characteristics of virtualized environment Virtualization reference model

1. Guest Characteristics of virtualized environmentVirtualization reference model Virtualization Layer Virtual Image Applications Physical Storage Applications Physical Networking Virtual Storage Virtual Hardware Virtual Networking Physical Hardware Software Emulation Host

2. Virtualization has three characteristics that make it ideal for cloud computing: • Partitioning: In virtualization, many applications and operating systems (OSes) are supported in a single physical system by partitioning (separating) the available resources. • Isolation: Each virtual machine is isolated from its host physical system and other virtualized machines. Because of this isolation, if one virtual-instance crashes, it doesn’t affect the other virtual machines. In addition, data isn’t shared between one virtual container and another. • Encapsulation: A virtual machine can be represented (and even stored) as a single file, so you can identify it easily based on the service it provides. In essence, the encapsulated process could be a business service. This encapsulated virtual machine can be presented to an application as a complete entity. Therefore, encapsulation can protect each application so that it doesn’t interfere with another application.

3. Increased security • Managed Execution A)Sharing B) Aggregation C)Emulation D)Isolation • Portability

4. Taxonomy of Virtualized Environment How it is done? Technique Virtualization Model Emulation Application Network Execution Environment Storage Process Level High-Level VM Programming Language Multiprogramming Operating System Virtualization Hardware-assisted Virtualization Full Virtualization System Level Hardware Paravirtualization …. Partial Virtualization

5. Execution virtualization1)Machine reference model Applications Applications API calls API Libraries Libraries User ISA ABI System calls User ISA Operative System Operative System ISA ISA Hardware Hardware

6. 2 Hardware Level virtualization Guest In memory representation Virtual Image Storage VMM Host emulation Virtual Machine binary translation instruction mapping interpretation …… Host

8. 3)Hardware Virtualization techniques • Hardware assisted virtualization • Full virtualization • Para virtualization • Partial virtualization

9. Hypervisors

10. 4) OS level virtualization offers the opportunity to create different and separated execution environments for applications that are managed concurrently. It is different from hardware virtualization —there is no virtual machine manager or hypervisor, and the virtualization is done within a single operating system, where the OS kernel allows for multiple isolated user space instances.

11. 5)Programming level virtualization is mostly used for achieving ease of deployment of applications, managed execution, and portability across different platforms and operating systems. It consists of a virtual machine executing the byte code of a program, which is the result of the compilation process.

12. 6)Application level virtualization Interpretation Binary Translation

13. Virtualization and cloud Server B (running) Server B (inactive) Server A (running) Server A (running) VM VM VM VM VM VM VM VM VM VM VM VM Virtual Machine Manager Virtual Machine Manager Before Migration After Migration

14. Advantage and disadvantage of virtualization Advantages: • Eliminates the need for numerous dedicated servers; • Cost effective because many times server software installation provisioning is available; • If one virtual server has a software failure, the other servers will not be affected; • Reduces energy costs because only one device is running instead of several; • Offers a flexibe IT infrastructure; • Can quickly make changes with little downtime.

15. Reduced spending. For companies with fewer than 1,000 employees, up to 40 percent of an IT budget is spent on hardware. Purchasing multiple servers is often a good chunk of this cost. Virtualizing requires fewer servers and extends the lifespan of existing hardware. This also means reduced energy costs. • Easier backup and disaster recovery. Disasters are swift and unexpected. In seconds, leaks, floods, power outages, cyber-attacks, theft and even snow storms can wipe out data essential to your business. Virtualization makes recovery much swifter and accurate, with less manpower and a fraction of the equipment – it’s all virtual. • More efficient IT operations. Going to a virtual environment can make everyone’s job easier – especially the IT staff. Virtualization provides an easier route for technicians to install and maintain software, distribute updates and maintain a more secure network. They can do this with less downtime, fewer outages, quicker recovery and instant backup as compared to a non-virtual environment. 

16. Disadvantages • Resource hogging could occur if there are too many virtual servers within a physical machine; • As software updates and patches must be compatible with everything running on the virtual machine, admins may have reduced control over the physical environment; • Administration, including backup and recovery, requires specialized knowledge; • If user experience is impacted, it can be difficult to identify the root cause; • Services offered by a dedicated server are more accessible.