July 3rd, 2014
Introduction & History
Basic Principles & Concepts
Types of Virtualization
Types of Hypervisor
• Proven software technology rapidly transforming IT Landscape.
• Fundamentally changing the way that people compute.
• Breaks the bond of traditional hardware computing systems.
• Revolutionizing the whole IT infrastructure ecosystem by transforming
Hardware into Software.
“Virtualization means to create a virtual version of a device or resource, such as
a server, storage device, network or even an operating system where the
framework divides the resource into one or more execution environments.
Devices, applications, human users are able to interact with the virtual resources
as if it were a real single logical resource.”
• Traces root back to 1960’s when Mainframe was King.
• Mainframe:Inflexible/Only one user at a time can feed mainframe a program.
• Tasks was batched into there own workloads.
• First Customer’s of Virtualization: THE BIRTH OF VIRTUALIZATION
• MIT: Project MAC(Mathematics and computation) later renamed to
Multiple Access Computer. $2 Million Grant:DARPA to fund research
specifically in areas of os, ai and computational theory.
• Bell LABS: Needed a Time Sharing System.
• IBM designed CP-40 main frame.Only used in Labs not for commercial.
• CP-67 evolved as the first commercial mainframe to support virtualization.
• S/360-67 CP/CMS first stable release in 1972
• CP-Control Program & CMS-Console Monitor System
In essence, virtualization lets you transform hardware into software. Use software such as
VMware ESX Server to transform or “virtualize” the hardware resources of an x86-based
computer—including the CPU, RAM, hard disk and network controller—to create a fully
functional virtual machine that can run its own operating system and applications just like a
Basic Principles & Concepts
• Virtualization allows a single physical server to simultaneously run multiple VMs.
• Each virtual machine is self-contained & protected from other VMs on the same server.
• Virtual machine appear to be real machines from outside world.
The Role of an OS
Abstract from the Hardware !
Basic Principles & Concepts
Same role than an OS
Virtualization has something more !
Memory Isolation from 'Outside'
Provides (Virtual) Access to Hardware
Can Handles Multiple Instances
Hypervisor (aka Virtual Machine Manager):
Program providing the virtualization platform.
Host OS (aka Supervisor):
Operating System on which is executed the Hypervisor.
Operating System executed inside the Hypervisor.
Virtual Machine (VM):
Instance of one environment provided by the Hypervisor.
Consolidating multiple physical servers into virtual servers that run on a single
A type of server virtualization technology which works at the OS layer. The physical
server and single instance of the operating system is virtualized into multiple isolated
partitions, where each partition replicates a real server. The OS kernel will run a
single operating system and provide that operating system functionality to each of
• Least Overhead.
• Highest Performance
• Highest Density
• Supports only one os as base and
• All os in the container should have
same version and same patch level of
the base os.
• Base os crash, guest becomes
• Examples: OpenVZ, Virtuozzo
In hardware emulation, a specialized software, which is also known as hypervisor,
creates hardware emulation for OS in a single server. They can host different types of
OS in a single server. The OS loaded into each virtual machine works as a standalone
and unmodified OS. When a VM (virtual machine) is running, the hypervisor make
changes to the part of the OS that make system calls. Hypervisor changes the OS by
entering a piece of code—which is known as binary translation- to the OS when it is
running. Binary translation takes place in four parts of the OS ( memory, processor,
network, storage) that interact with the hardware.
• You do not have to modify the OS and applications to run on the virtual
• Example: VMware
A hypervisor is a hardware virtualization technique that allows multiple guest
operating systems (OS) to run on a single host system at the same time. The guest OS
shares the hardware of the host computer, such that each OS appears to have its own
processor, memory and other hardware resources.
• A hypervisor is also known as a virtual machine manager (VMM).
• Term Coined by IBM.
Type 1 Hypervisor
Type 1 hypervisor is also known as bare-metal implementation because they sit directly
on the top of hardware, without needing any operating system. Since they can directly
communicate with hardware resources, they are much faster than type 2 hypervisor.
• Single virtual machine crash does not
affect rest of guest system.
• More Secure than type2.
• Generate less overhead and fast.
• Example:Vmware Esx, Microsoft Hyper-V
Type 2 Hypervisor
Type 2 hypervisor resides on top of the operating system. Since they cannot directly
communicate with the hardware, they are less efficient than the type 1.
• Install is easier.
• OS takes care of all the hardware,
that’s why can support wide range of
• More points of failure, anything that
affects the stability of base os can also
affect the guest os.
Example: Vmware Player and Workstation
Paravirtualization does not emulate hardware environment in software, instead it
coordinates or multiplexes access to hardware resources in favor of virtual machine.
In paravirtualized environment, a guest OS( called DomainU) is directly installed on the
hypervisor(bare-metal architecture) that does not contain any device drivers for
network and storage. Instead a privileged guest OS-also known as DomainO-has direct
access to hardware. All guest OSes access hardware resources via DomainO). When a
guest OS(virtual machine) needs to access hardware resources it sends a message to
DomianO that access the hardware on behalf of guest OS. When data returns to the
hardware, DomainO reads the information and passes it back to the guest operating
system that has request it.
DomainO is a standard OS such as Linux that has been modified to communicate with
hypervisor to control access to hardware.
Application virtualization is relatively simple in that an application runs on your desktop without
ever having installed it. However, unlike using Terminal Services, the virtualized application
executes locally, using local resources (e.g., processor, memory, disk, and network card). In other
words, the application runs, saves data, prints, and acts as if it’s installed locally even though it is
not. On top of this, you can run multiple versions of the same application on your desktop
without conflict, and run conflicting applications like different versions of Access or Outlook with
out conflict—again, with all the applications executing locally – and not as “screen scrapes” from
a remote Terminal Server.
AppV is best utilized if the clients machines are more powerful and you do not need very
The term "Presentation Virtualization" is used to cover technologies like Microsoft Terminal Server
or Citrix MetaFrame/Presentation Server/XenApp. Also, any Remote Desktop Connection (like RDP
to remote PCs, VNC..) are considered as Presentation Virtualization. From the Client's perspective,
in Presentation Virtualization the application runs on a remote computer (literally consumes RAM
and CPU resources there) but the User Interface (Windows output, Mouse+Keyboard input) are
transmitted over the network to the Client (on the Client the is only the "Presentation layer" of an
Presentation Server is best if you are using thin clients and wants to use everything on the server
With network virtualization, the network is “carved up” and can be used for multiple purposes
such as running a protocol analyzer inside an Ethernet switch. Components of a virtual network
could include NICs, switches, VLANs, network storage devices, virtual network containers, and
With storage virtualization, the disk/data storage for your data is consolidated to and managed
by a virtual storage system. The servers connected to the storage system aren’t aware of where
the data really is. Storage virtualization is sometimes described as “abstracting the logical
storage from the physical storage.
Virtualization Survey 2013 Q3
• VMware continues to dominate the virtualization space with over 54% market share.
• More than 75% of their entire IT infrastructure is now virtualized.
• 12% of those surveyed admitted to using Xen and KVM, leading open source virtualization
• 52% of respondents indicated that their preferred private cloud supplier was VMware.