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

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

Taxonomoy 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; • Offers the ability for different domain names, file directories, email administration, IP addresses, logs and analytics; • 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.

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.