Characteristics of virtualized environment Virtualization reference model Guest

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

• 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 virtualinstance 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.

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

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

Execution virtualization 1)Machine reference model Applications API calls API Libraries User ISA System calls ABI User ISA Operative System ISA Hardware

2 Hardware Level virtualization In memory representation Host emulation binary translation instruction mapping interpretation ……

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

Hypervisors

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.

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.

6)Application level virtualization Interpretation Binary Translation

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

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.

• 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.

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.