This document discusses the concepts of traditional physical servers versus virtual servers. With traditional servers, each application runs on dedicated physical hardware. If a server fails or runs out of resources, a new physical server must be added. Virtualization allows multiple virtual servers to run isolated on the same physical hardware using a hypervisor. This improves scalability, availability, and efficiency compared to traditional servers. Some benefits of virtual servers include rapid deployment, live migration, high availability, and optimizing physical resources. While virtualization is more complex conceptually, it reduces costs over traditional servers in the long run.

1. Mahesh Aravapalli
mahesharavapalli@yahoo.com

2. SECTION:

3. The Traditional Server Concept
System
Administrators
often talk about
servers as a
whole unit that
includes the
hardware, the
OS, the storage,
and the
applications.
• Servers are often referred to by their function i.e. the Exchange
server, the SQL server, the File server, etc.
• If the File server fills up, or the Exchange server becomes overtaxed,
then the System Administrators must add in a new server.

4. The Traditional Server Concept
System Admins can implement clusters of servers to make
them more fault tolerant. However, even clusters have limits
on their scalability, and not all applications work in a
clustered environment.
Unless there are multiple
servers, if a service
experiences a hardware
failure, then the service is
down.

5. The Traditional Server Concept
• Pros
– Easy to conceptualize
– Fairly easy to deploy
– Easy to backup
– Virtually any
application/service can be
run from this type of setup
• Cons
– Expensive to acquire and maintain
hardware
– Not very scalable
– Difficult to replicate
– Redundancy is difficult to implement
– Vulnerable to hardware outages
– In many cases, processor is under-
utilized

6. SECTION:

7. What is Virtualization ?
• Virtualization is way to run multiple operating systems and user
applications on the same hardware
– E.g., run both Windows and Linux on the same laptop
• How is it different from dual-boot?
– Both OSes run simultaneously
• The OSes are completely isolated from each other

8. Uses of Virtualization
• Server consolidation
– Run a web server and a mail server on the same physical server
• Easier development
– Develop critical operating system components (file system, disk driver) without
affecting computer stability
• QA
– Testing a network product (e.g., a firewall) may require tens of computers
– Try testing thoroughly a product at each pre-release milestone… and have a straight
face when your boss shows you the electricity bill

9. Types of Hypervisors
• Definitions
– Hypervisor (or VMM – Virtual Machine Monitor) is a software layer
that allows several virtual machines to run on a physical machine
– The physical OS and hardware are called the Host
– The virtual machine OS and applications are called the Guest, which
is managed by the Hypervisor
VMware ESX, Microsoft Hyper-V, Xen
Hardware
Hypervisor
VM1 VM2
Type 1 (bare-metal)
Host
Guest
Hardware
OS
Process Hypervisor
VM1 VM2
Type 2 (hosted)
VMware Workstation, Microsoft Virtual PC,
Sun VirtualBox, QEMU, KVM
Host
Guest

10. The Virtual Server Concept
• Virtual servers can still be referred to by their function i.e. email server,
database server, etc.
• If the environment is built correctly, virtual servers will not be affected
by the loss of a host.
• Hosts may be removed and introduced almost at will to accommodate
maintenance.
• Virtual servers can be scaled out easily.
– If the administrators find that the resources supporting a virtual server are
being taxed too much, they can adjust the amount of resources allocated
to that virtual server
• Server templates can be created in a virtual environment to be used to
create multiple, identical virtual servers
• Virtual servers themselves can be migrated from host to host almost at
will.

11. The Virtual Server Concept
• Pros
– Resource pooling
– Highly redundant
– Highly available
– Rapidly deploy new servers
– Easy to deploy
– Reconfigurable while services
are running
– Optimizes physical resources
by doing more with less
• Cons
– Slightly harder to conceptualize
– Slightly more costly (must buy
hardware, OS, Apps, and now the
abstraction layer)

12. Types of Virtualization
• Server Virtualization
• Desktop Virtualization
• Application Virtualization
• Memory
• Storage
• Data
• Network

13. Server Virtualization
Pain Area
• Maintaining Spares
• Administrators
• Backup / Restore
• Rebuild OS
Data Recovery
• Disaster Recovery
• Same Vendor
• Same Model
Solution • Consolidation
• Shared CPU, Memory, NIC ,DISK
• Maximum utilization – 70% (Avg)
• Centralized Management
• Migration
• Less space
• Less TCO
• Fast ROI

14. Server Virtualization Benefits
Benefits
• Host servers connected over SAN
• Hardware fail tolerance
• High availability
• Online live migration
• Easy management
• Disaster Recovery
• Easily scalable, Adjustable
• Different Vendor, Type, Model
servers controlled by Hypervisor
• Less hardware management /
maintenance cost
• Better efficiency with less cost
• Maintain average utilization %
How it Looks

15. Desktop Virtualization
• Same as server Virtualization
• User’s desktop runs on data servers as Virtual machines
• Secured by design
• Multiple OSes runs on same Hypervisor host
• Centralized management
• Shared resources with maximum utilization
• Supports multimedia / memory intensive apps on VM

16. Desktop Virtualization Benefits
Benefits
• Centralized Service pack upgrade / OS
patch installation
• OS upgrade from one version to
another
• High availability
• Fault tolerance
• Thin / Thick provisioned storage
• Accessed via LAN, WAN, Internet &
Mobile
• Offline use with help of VMPlayer /
XenClient on Desktop, Laptop and
ThinClients.
Local Client Devices Virtual Desktops in Datacenter

17. Application Virtualization
• Business applications runs on
servers located in datacenter
• Secured by design
• One / more apps runs on same set
of servers
• Centralized application management
• Shared resources with maximum
utilization
• Supports multimedia / memory
intensive apps
• Reduces licensing cost
• Role based user access controlled
by policies
How it works

18. Application Virtualization Benefits
• Applications delivered on-demand
• No need to install and manage on every user desktop
• Increased performance
• Easily upgraded and deliver instantly
• Published either locally installed or steamed to server
• Offline access via streamed on client machines with help of offline plug-in
• Role based application functionality • Multiple version of same application
accessibility
• Application isolation
• Accessed via LAN, WAN, Internet & Mobile
• Content Redirection
• Server to client
• Client to server

19. Virtualization Vendors – Most Popular
Server Virtualization
• VMWare ESX
• Citrix XenServer
• Microsoft Hyper-V
• Red hat RHEV
Desktop Virtualization
• Citrix XenDesktop
• Citrix VDI-in-a-Box
• VMWare view
• VMWare VDI-in-a-Box
• Microsoft VDI
• Redhat RHEV for
Desktops
Application Virtualization
• Citrix XenApp
• VMWare ThinApp
• Microsoft App-V

20. Q & A