This presentation tries to explain basics of virtualization, what is server virtualization ? why is it important ? how it is done ? What are the limitations and risks associated with it ?

1. Server Virtualization
by Siddharth Bhatt
sidbhatt11@yahoo.in
www.siddharthbhatt.com

2. Contents
• Virtualization - Definition, Types of Virtualization
• Server Virtualization - What ? How ? Why ?
• Server Virtualization - Limitations & Risks
• List of Sources

3. Virtualization : Definition
• Virtualization, in computing, refers to the act of creating a virtual
(rather than actual) version of something, including but not limited to
a virtual computer hardware platform, operating system (OS), storage
device, or computer network resources.
• Virtualization began in 1960s mainframe computers as a method of
logically dividing the system resources provided by mainframes
between different applications. Since then, the meaning of the term
has broadened

4. Virtualization : Types
• Software
• OS Level Virtualization
• Application Virtualization
• Service Virtualization
• Memory
• Memory virtualization, aggregating random-access memory (RAM) resources from
networked systems into a single memory pool
• Virtual memory, giving an application program the impression that it has contiguous
working memory, isolating it from the underlying physical memory implementation

5. Virtualization : Types
• Storage
• Storage virtualization, the process of completely abstracting logical storage from physical
storage
• Distributed file system, any file system that allows access to files from multiple hosts
sharing via a computer network
• Virtual file system, an abstraction layer on top of a more concrete file system, allowing client
applications to access different types of concrete file systems in a uniform way
• Storage hypervisor, the software that manages storage virtualization and combines physical
storage resources into one or more flexible pools of logical storage
• Virtual disk drive, a computer program that emulates a disk drive such as a hard disk drive
or optical disk drive

6. Virtualization : Types
• Data
• Data virtualization, the presentation of data as an abstract layer, independent of underlying
database systems, structures and storage
• Database virtualization, the decoupling of the database layer, which lies between the storage
and application layers within the application stack over all
• Network
• Network virtualization, creation of a virtualized network addressing space within or across
network subnets
• Virtual private network (VPN), a network protocol that replaces the actual wire or other physical
media in a network with an abstract layer, allowing a network to be created over the Internet

7. Server Virtualization : What ? & How
?
• Server virtualization can be defined as the conversion of one physical server into several
individual & isolated virtual spaces that can be taken up by multiple users as per their
respective requirements.
• There are three ways to create virtual servers:
1. Full virtualization
2. Para-virtualization
3. OS-level virtualization
• They all share a few common traits. The physical server is called the host. The virtual
servers are called guests. The virtual servers behave like physical machines. Each system
uses a different approach to allocate physical server resources to virtual server needs

8. Full Server Virtualization
• Full virtualization uses a special kind of
software called a hypervisor. The
hypervisor interacts directly with the
physical server's CPU and disk space.
It serves as a platform for the virtual
servers' operating systems. The
hypervisor keeps each virtual server
completely independent and unaware
of the other virtual servers running on
the physical machine. Each guest
server runs on its own OS -- you can
even have one guest running on Linux
and another on Windows.

9. Full Server Virtualization
• The hypervisor monitors the physical
server's resources. As virtual servers
run applications, the hypervisor
relays resources from the physical
machine to the appropriate virtual
server. Hypervisors have their own
processing needs, which means that
the physical server must reserve
some processing power and
resources to run the hypervisor
application. This can impact overall
server performance and slow down
applications

10. Para Server Virtualization
• The para-virtualization approach is a
little different. Unlike the full
virtualization technique, the guest
servers in a para-virtualization system
are aware of one another. A para-
virtualization hypervisor doesn't need
as much processing power to manage
the guest operating systems, because
each OS is already aware of the
demands the other operating systems
are placing on the physical server.
The entire system works together as a
cohesive unit.

11. OS-Level Virtualization
• An OS-level virtualization approach
doesn't use a hypervisor at all. Instead,
the virtualization capability is part of the
host OS, which performs all the
functions of a fully virtualized
hypervisor. The biggest limitation of this
approach is that all the guest servers
must run the same OS. Each virtual
server remains independent from all the
others, but you can't mix and match
operating systems among them.
Because all the guest operating
systems must be the same, this is
called a homogeneous environment.

12. Server Virtualization : Why ?
• Server virtualization conserves space through consolidation. It's
common practice to dedicate each server to a single application. If
several applications only use a small amount of processing power,
the network administrator can consolidate several machines into one
server running multiple virtual environments. For companies that
have hundreds or thousands of servers, the need for physical space
can decrease significantly.

13. Server Virtualization : Why ?
• Server virtualization provides a way for companies to practice
redundancy without purchasing additional hardware. Redundancy
refers to running the same application on multiple servers. It's a
safety measure -- if a server fails for any reason, another server
running the same application can take its place. This minimizes any
interruption in service. It wouldn't make sense to build two virtual
servers performing the same application on the same physical server.
If the physical server were to crash, both virtual servers would also
fail. In most cases, network administrators will create redundant
virtual servers on different physical machines.

14. Server Virtualization : Why ?
• Virtual servers offer programmers isolated, independent systems in
which they can test new applications or operating systems. Rather
than buying a dedicated physical machine, the network administrator
can create a virtual server on an existing machine. Because each
virtual server is independent in relation to all the other servers,
programmers can run software without worrying about affecting other
applications.

15. Server Virtualization : Why ?
• Server hardware will eventually become obsolete, and switching from
one system to another can be difficult. In order to continue offering
the services provided by these outdated systems (sometimes called
legacy systems) a network administrator could create a virtual
version of the hardware on modern servers. From an application
perspective, nothing has changed. The programs perform as if they
were still running on the old hardware. This can give the company
time to transition to new processes without worrying about hardware
failures, particularly if the company that produced the legacy
hardware no longer exists and can't fix broken equipment.

16. Server Virtualization : Why ?
• An emerging trend in server virtualization is called migration.
Migration refers to moving a server environment from one place to
another. With the right hardware and software, it's possible to move a
virtual server from one physical machine in a network to another.
Originally, this was possible only if both physical machines ran on the
same hardware, operating system and processor. It's possible now to
migrate virtual servers from one physical machine to another even if
both machines have different processors, but only if the processors
come from the same manufacturer.

17. Server Virtualization : Limitations
• There's a limited amount of disk space and CPU Power available on
physical servers. Too many virtual servers could impact the server's
ability to store & process data.
• Another limitation is migration. Right now, it's only possible to migrate
a virtual server from one physical machine to another if both physical
machines use the same manufacturer's processor. If a network uses
one server that runs on an Intel processor and another that uses an
AMD processor, it's impossible to port a virtual server from one
physical machine to the other.

18. Server Virtualization : Security
Risks
• Blue Pill : This occurs when a virtual machine masquerades as a
hypervisor by installing itself on a host machine. As a result, resource
allocations and interactions between virtual OS instances are
controlled by the virtual machine acting as an imposter.
• SubVirt : Is a VM rootkit that positions itself on the physical machine.
It then monitors and records the activity of the VM. As a result, it
disguises when the system is compromised and also may involve
other threatening programs like spyware or keystroke loggers.

19. Server Virtualization : Security
Risks
• Denial-of-Service : This is a virtual machine infrastructure attack that
allows a single or multiple VMs to consume all of the resources that
are contained within the host machine. Thus, these resources would
not be available for other VMs.
• Trojan : In this case, a hacker compromises the virtual machine
manager, which allows them to control the applications and operating
systems that are found on the machines, which is generally not
addressed by anti-virus software.

20. List of Sources
• Botelho, Bridget. "AMD pushes VMware et al. to broaden live migration."
SearchServerVirtualization. Aug. 29, 2007. Retrieved on March 18, 2008.
http://articles.techrepublic.com.com/5100-10879_11-6074941.html
• McAllister, Neil. "Server virtualization." InfoWorld. Feb. 12, 2007. Retrieved March 12, 2008.
http://www.infoworld.com/article/07/02/12/07FEvirtualserv_1.html
• Ou, George. "Introduction to server virtualization." Tech Republic. May 22, 2006. Retrieved March
17, 2008. http://articles.techrepublic.com.com/5100-10879_11-6074941.html
• Perilli, Alessandro. "Step-by-step virtualization: Addressing all phases of adoption."
SearchServerVirtualization. June 1, 2006. Retrieved March 18, 2008.
http://searchservervirtualization.techtarget.com/tip/0,289483,sid94_ gci1191541,00.html
• Singh, Amit. "An Introduction to Virtualization." Kernelthread.com. Retrieved March 18, 2008.
http://www.kernelthread.com/publications/virtualization/

21. List of Sources
• Stansberry, Matt. "CIO primer: Virtualization basics."
SearchServerVirtualization. Jan. 4, 2006. Retrieved March 18, 2008.
• Margaret Rouse, WhatIs.com,
http://searchservervirtualization.techtarget.com/definition/server-
virtualization
• Roger Grimes, http://www.infoworld.com/article/2614369/security/the-5-
cloud-risks-you-have-to-stop-ignoring.html
• cmeier and mnovellino,
http://cybersecurity.mit.edu/2013/09/virtualization-awareness-and-
security-threats/

22. Thank You !
by Siddharth Bhatt
sidbhatt11@yahoo.in
www.siddharthbhatt.com