What is Virtualization?

What is Virtualization? Virtualization is a technique how to

separate a service from the underlying physical delivery of that service

It was first developed in the 60’s by IBM Until 1998 it was considered impossible

for microprocessors (x86) based computers The inventors of x86 virtualization created

VMware in 1998 in Palo Alto Behind a company, there is an idea!

What is Virtualization?• Virtualization

• Decouples software from hardware

• Allows multiple operating systems to be installed on the “host” computer

Virtualization

2 Approaches for x86 Virtualization

Hosted: virtualization layer runs as anapplication on top of an operating system

Hypervisor (bare-metal): installs the virtualization layer directly on a x86 based system

Hypervisor is more efficient, more robust and has greater scalability and better

performance than hosted architecture

Virtualization Layer: VMM The virtualization layer is responsible for

hosting and managing all virtual machines VMM (virtual machine monitors) are the

interfaces between the guest operating systems and the Hypervisor running on the hardware

VMM implement the hardware abstraction Each VMM has to partition and share CPU,

memory and I/O devices used by the systems

The Challenge of x86 Virtualization

x86 (microprocessor) operating systems are designed to run directly on the hardware

They assume that they fully “own” the computer

Three Alternative Techniques

Full virtualization using binary translation

Operating system assisted virtualization

(para-virtualization)

Hardware assisted virtualization

Virtualization with Binary Translation

Translates kernel code to replace non virtualizable instructions with new sequences

Guest OS is not aware of what takes place

OS Assisted: Para-virtualization

Modify the guest operating system (kernel) to replace non-virtualizable instructions with calls to the virtualization layer

Hardware Assisted

Hardware vendors developed ad-hoc processors which support the

virtualization layer

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May 2, 2023

What is a Virtual Appliance?

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VMWare

Application

Operating System

VMWare

Application

Operating System

VMWare

Application

Operating SystemAn application plus an operating system, pre-configured, bundled together. VMware allows multiple applications to run simultaneously on a single server.

Virtualization with VMware ESX 3.5

Needs a dedicated server !

Each virtual machine represents a complete system – with processor, memory, network interface card, storage and BIOS

Windows, Linux, Netware etc. with their software applications run totally isolated from each other

Virtual machines see their own private virtual disk files; outside, the virtual disks are simply large files

VMware ESX installs directly on the server hardware, or “bare metal” and insertsa virtualization layer between the hardware and the operating system

Physical resources such as paging memory are shared between the VM’s on ESX

Virtualization with VMware Server

Runs on Windows or Linux as an application

Available for free !

Best choice for test environment on an existing server

Otherwise works like VMware ESX