Cloud Computing
Lecture 5-6
Muhammad Ahmad Jan
Lecture Outline
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Why Virtualization
Virtualization
Hypervisor and its types
Types of virtualization
Virtualization Products
Example…
Problem
• Enterprise IT centers support many service applications
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Microsoft Exchange
Oracle
SAP
Web servers
…
• Each service application demands its own environment
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Specific version of operating system
Multiple processors and disks
Specialized configurations
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• Combining services on same server host is difficult (at best)
• Conflicting demands
• Incompatible loads
• ….
Problem …
• Adding or upgrading hardware or OS is
difficult
• Testing and refitting active service
• Complicated changeover tactics
•…
• Load balancing is impossible
• Services tied to own systems
• Some underused, some overused
Modest Example
• Approx 20 difference services
• Approx 20 server systems
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multiple processors
> 100 gigabytes of RAM
~ 20 terabytes of disk storage
Multiple operating systems
Solution - Virtualization
• Decouple [OS, service] pair from hardware
• Multiplex lightly-used services on common
host hardware
• Migrate services from host to host as needed
• Introduce new [OS, service] pairs as needed
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Commissioning new services
Testing upgrades of existing services
Experimental usage
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Virtualization
 Virtualization is the ability to run multiple operating
systems on a single physical system and share the
underlying hardware resources.
 It is the process by which one computer hosts the
appearance of many computers.
 Virtualization is used to improve IT throughput and
costs by using physical resources as a pool from which
virtual resources can be allocated.
Virtualization
Benefits of Virtualization
 Sharing of resources helps cost reduction
 Isolation: Virtual machines are isolated from each other as if
they are physically separated
 Encapsulation: Virtual machines encapsulate a complete
computing environment
 Hardware Independence: Virtual machines run independently
of underlying hardware
 Portability: Virtual machines can be migrated between
different hosts.
Virtualization in Cloud Computing
Cloud computing takes virtualization one step further:
• You don’t need to own the hardware
• Resources are rented as needed from a cloud
• Various providers allow creating virtual servers:
– Choose the OS and software each instance will have
– The chosen OS will run on a large server farm
– Can instantiate more virtual servers or shut down existing
ones within minutes
• You get billed only for what you used
Hypervisor
• The hypervisor (also called a virtual machine monitor) is the
low-level program that allows multiple operating systems to run
concurrently on a single host computer.
• Hypervisors use a thin layer of code in software or firmware to
allocate resources in real-time.
• Its just like a traffic cop that controls I/O and memory
management.
• Hypervisor can perform VM creation, Resource allocation
(CPU, memory, Disks), VM migration and destruction etc.
Type 1 Hypervisor
• Type 1 hypervisors run directly on the system hardware. They
are often referred to as a "native" or "bare metal" or
"embedded" hypervisors.
Type 2 Hypervisor
• Type 2 hypervisors run on a host operating system. When the
virtualization movement first began to take off, Type 2
hypervisors were most popular.
• Administrators could buy the software and install it on a server
they already had.
Two Approaches
Difference b/w Type 1 and Type 2 hypervisors
• Type 1 hypervisors are gaining popularity because building the
hypervisor into the firmware is proving to be more efficient.
• According to IBM, Type 1 hypervisors provide higher
performance, availability, and security than Type 2 hypervisors.
• IBM recommends that Type 2 hypervisors be used mainly on
client systems where efficiency is less critical or on systems
where support for a broad range of I/O devices is important and
can be provided by the host operating system.
Experts’ Prediction
• Experts predict that shipping hypervisors on bare metal will
impact how organizations purchase servers in the future.
• Instead of selecting an OS, they will simply have to order a
server with an embedded hypervisor and run whatever OS they
want.
Virtualization - Basic Terminologies
Host Machine – Physical machine that hosts one or more virtual
machines.
Virtual Machine (Guest VM) – A self-contained software
emulation of a machine, which does not physically exist, but
shares resources of an underlying physical machine.
VM Cluster – A collection of VM Hosts that act as a single large
host. If one of the hosts are removed, all of the VMs that the host
was running seamlessly continue running on the other hosts. A true
VM cluster requires shared storage such as a SAN/NAS device.
P2V (Physical to Virtual) – Refers to the process of migrating
operating systems, applications and data from the hard disk of a
physical server to a virtual machine.
Virtualization - Basic Terminologies
VM Snapshot – Preserves the state and data of a virtual machine
at a given point in time, allowing for recovery at a single point in
time for a VM. Snapshots are NOT a way to do backups, but part
of the technology used to create snapshots are used by backup
software to do backups correctly.
VM Backup – Virtual machine backup can be performed multiple
different ways depending on the backup software and the type of
hypervisor that the VM guest resides on. The backup
software guards against data loss and can be used to recover files
in the event of hardware failure or other disaster.
VM Replication – The ability to replicate virtual machines at the
server virtualization level using replication software. Provides
redundancy for quick VM recovery and reduced downtime in the
event of failure or disaster.
Attributes of All Virtual Machines
Software Compatibility – Provides compatible abstraction so all
software written for the machine that VM is virtualizing will run in
it .
• Java – “Write once Run anywhere”
Isolation – All software running on the VM is contained within it
and can’t affect other VMs or processes.
Performance – Any new software layer adds overhead to the
system.
Types of Virtualization
• Server Virtualization
• Application Virtualization
• Network Virtualization
• Storage Virtualization
• Desktop Virtualization
• Virtual Desktop Infrastructure (VDI)
Server Virtualization
• Partitioning of a physical server into smaller virtual servers in
order to better utilize server resources.
Application Virtualization
• The separation of the installation of an application from the
underlying operating system on which it is executed.
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Application virtualization is layered on top of other
virtualization technologies, allowing computing resources to be
distributed dynamically in real-time.
Network Virtualization
• The process of combining hardware and software network
resources to create a single pool of resources that make up a
virtual network that can be accessed without regard to the
physical component.
Storage Virtualization
• The process of consolidating
the physical storage from
multiple
network
storage
devices so that it appears to be
a single storage unit.
Desktop Virtualization
• The
process
of
virtualizing
desktop
computers
using
virtualization software, such that the desktop computer and the
associated operating system and applications are separated from
the physical client device that is used to access it.
Virtual Desktop Infrastructure (VDI)
• The practice of hosting a desktop environment within a virtual
machine that runs on a centralized or remote server.
Products
 For the Enterprise
• VMware ESX/vSphere, Virtual Center
• Microsoft HyperV
 For the end user
• VMware Player, Server
• Oracle Virtualbox
• QEmu (Quick Emulator)
• Microsoft Virtual PC
Finally, there are other products besides these and many
more to appear especially with the explosion of cloud
computing
Example – VirtualBox (Step-1)
Example – VirtualBox (Step-2)
Example – VirtualBox (Step-3)
Creating VM – Step 1
Creating VM – Step 2
Creating VM – Step 3
Creating VM – Step 4
Creating VM – Step 5
The End