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

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

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

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

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

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 Server A (running) VM Server B Virtual Machine Manager (inactive) Before Migration 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.