Virtualization is a technique that separates a service from the underlying physical hardware. It allows multiple operating systems to run simultaneously on a single computer by decoupling the software from the hardware. There are two main approaches - hosted virtualization runs atop an operating system, while hypervisor-based virtualization installs directly on the hardware for better performance and scalability. A virtualization layer called a VMM manages and partitions CPU, memory, and I/O access for the guest operating systems. Virtualization overcomes the challenge that x86 operating systems assume sole ownership of the hardware through techniques like binary translation, para-virtualization with OS assistance, or newer hardware-assisted virtualization.

1. What is Virtualization?

2. 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!

3. What is Virtualization?
• Virtualization
• Decouples software
from hardware
• Allows multiple
operating systems to
be installed on the
“host” computer
Virtualization

4. 2 Approaches for x86 Virtualization
 Hosted: virtualization layer runs as an
application 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

5. 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

6. 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

7. Three Alternative Techniques
 Full virtualization using binary translation
 Operating system assisted virtualization
(para-virtualization)
 Hardware assisted virtualization

8. Virtualization with Binary Translation
 Translates kernel code to replace non
virtualizable instructions with new
sequences
 Guest OS is not aware of what takes place

9. OS Assisted: Para-virtualization
 Modify the guest operating system
(kernel) to replace non-virtualizable
instructions with calls to the virtualization
layer

10. Hardware Assisted
 Hardware vendors developed ad-hoc
processors which support the
virtualization layer

11. 11
April 13, 2016
What is a Virtual Appliance?
11 04/13/16
VMWareVMWare
ApplicationApplication
Operating SystemOperating System
VMWareVMWare
ApplicationApplication
Operating SystemOperating System
VMWareVMWare
ApplicationApplication
Operating SystemOperating System
An application plus an operating
system, pre-configured, bundled
together. VMware allows multiple
applications to run simultaneously
on a single server.

12. 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 inserts
a virtualization layer between the hardware and the operating system
 Physical resources such as paging memory are shared between the VM’s on ESX

13. 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