Virtualization allows multiple operating systems to run on a single physical machine by dividing the machine's resources among virtual environments. Cloud computing takes virtualization further by allowing users to rent computing resources from large data centers as needed rather than owning their own hardware. This allows users to pay only for the resources they use and scale up or down easily based on demand. Virtualization and cloud computing provide benefits like cost control, business agility, and reducing the need for companies to manage their own IT infrastructure.

1. Virtualization and
Cloud Computing
By Josh Folgado
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JoshFolgado–BusinessEnterpriseArchitect(http://joshfolgado.com)

2. JoshFolgado–BusinessEnterpriseArchitect
2
Client
Endpoints
Devices
Public
End Users
Management
OS / Apps / Data
Infrastructure
and Services
On-Premise
Off-Premise
Traditional IT Environment

3. 3Source: Foresights Budgets And Priorities Tracker Survey, Q2 2012
Q. Which of the following initiatives are likely to be your IT
organization top technology priorities over the next 12 months?
% critical or
high priority
Top IT Priorities
• BC/DR
• Security
• Consolidation
• Virtualization and
automation
Top Technology Priorities
JoshFolgado–BusinessEnterpriseArchitect

4. 4
Challenges of Traditional Computing Environments
Cost and complexity restricts the solution
• Some applications are left unprotected
• No easy way to test = unpredictable results in the event of
an outage
1:1 ratio of server/OS/application
• Low resource utilization across IT environment
• Server sprawl = Increasing cost and complexity
• Difficult to scale applications to keep up with demands
Keeping applications available, optimized
• Silos of applications = silos of solutions for protection
• A comprehensive BCDR solution can be multi tiered and complex
• Lack of comprehensive visibility across the IT infrastructure
JoshFolgado–BusinessEnterpriseArchitect

5. The Traditional Server Concept
5
Web Server
Windows
IIS
App Server
Linux
Glassfish
DB Server
Linux
MySQL
Email
Windows
Exchange
JoshFolgado–BusinessEnterpriseArchitect

6. And if something goes wrong ...
6
Web Server
Windows
IIS
App Server
DOWN!
***
DB Server
Linux
MySQL
Email
Windows
Exchange
JoshFolgado–BusinessEnterpriseArchitect

7. 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
exceeds capacity then the System Administrators
must add in a new server
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JoshFolgado–BusinessEnterpriseArchitect

8. The Traditional Server Concept
Unless there are multiple servers, if a service
experiences a hardware failure then the service is
down
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
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JoshFolgado–BusinessEnterpriseArchitect

9. 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
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JoshFolgado–BusinessEnterpriseArchitect

10. Two Technologies for Agility
Virtualization:
The ability to run multiple operating systems on a
single physical system and share the underlying
hardware resources*
Cloud Computing:
“The provisioning of services in a timely (near on
instant), on-demand manner, to allow the scaling up
and down of resources”**
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* VMware white paper, Virtualization Overview
** Alan Williamson, quoted in Cloud BootCamp March 2009
JoshFolgado–BusinessEnterpriseArchitect

11. 11
Strategic Computing Architecture
One Platform to Solve a Range of Pressing
Challenges Across a Range of Environments and Users
Server
Consolidation
Virtualized Infrastructure (i.e. VMware)
Business
Continuity
Rapid
Provisioning
Enterprise
Desktops
Server Storage Network
JoshFolgado–BusinessEnterpriseArchitect

12. Definitons
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 Virtualization
A layer mapping its visible interface and resources onto the interface and
resources of the underlying layer or system on which it is implemented
Purposes:
 Abstraction – to simplify the use of the underlying resource (e.g.,
by removing details of the resource’s structure)
 Replication – to create multiple instances of the resource (e.g., to
simplify management or allocation)
 Isolation – to separate the uses which clients make of the
underlying resources (e.g., to improve security)
 Virtual Machine Monitor (VMM)
A virtualization system that partitions a single physical “machine” into
multiple virtual machines.
Terminology:
 Host – the machine and/or software on which the VMM is
implemented
 Guest – the OS which executes under the control of the VMM
JoshFolgado–BusinessEnterpriseArchitect

13. What is Virtualization
Virtualization allows one computer to do the job
of multiple computers
Virtual environments let one computer host
multiple operating systems at the same time
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JoshFolgado–BusinessEnterpriseArchitect

14. How does Virtualization work
Virtualization transforms hardware into software
It is the creation of a fully functional virtual
computer that can run its own applications and
operating system
Creates virtual elements of the CPU, RAM, and
hard disk
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JoshFolgado–BusinessEnterpriseArchitect

15. Origins – Virtualization Technology
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 Concurrent execution of multiple production operating systems
 Testing and development of experimental systems
 Adoption of new systems with continued use of legacy systems
 Ability to accommodate applications requiring special-purpose OS
 Introduced notions of “handshake” and “virtual-equals-real
mode” to allow sharing of resource control information with CP
 Leveraged ability to co-design hardware, VMM, and Guest OS
IBM Systems Journal, vol. 18, no. 1, 1979, pp. 4-17.
JoshFolgado–BusinessEnterpriseArchitect

16. Virtualization
Architecture & Interfaces
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 Architecture: formal specification of a system’s interface and the
logical behavior of its visible resources.
Hardware
System ISA User ISA
Operating
System
System Calls
Libraries
Applications
ISA
ABI
API
 API – application binary interface
 ABI – application binary interface
 ISA – instruction set architecture
JoshFolgado–BusinessEnterpriseArchitect

17. Virtualization
VMM Types
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• System
 Process
 Provides ABI interface
 Efficient execution
 Can add OS-independent services
(e.g., migration, intrusion
detection)
 Provides API interface
 Easier installation
 Leverage OS services (e.g.,
device drivers)
 Execution overhead (possibly
mitigated by just-in-time
compilation)
JoshFolgado–BusinessEnterpriseArchitect

18. Virtualization
System-level Design Approaches
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 Full virtualization (direct execution)
• Exact hardware exposed to OS
• Efficient execution
• OS runs unchanged
• Requires a “virtualizable” architecture
• Example: VMware
 Para-virtualization
 OS modified to execute under VMM
 Requires porting OS code
 Execution overhead
 Necessary for some (popular)
architectures (e.g., x86)
 Examples: Xen, Denali
JoshFolgado–BusinessEnterpriseArchitect

19. Virtualization
Desing Space – (Level vs. ISA)
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 Variety of techniques and approaches available
 Critical technology space highlighted
API interface ABI interface
JoshFolgado–BusinessEnterpriseArchitect

20. Virtualization
System VMMs
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 Structure
• Type 1: runs directly on host hardware
• Type 2: runs on Host OS
 Primary goals
• Type 1: High performance
• Type 2: Ease of
construction/installation/acceptability
• Examples
• Type 1: VMware ESX Server, Xen, OS/370
• Type 2: User-mode Linux
Type 1
Type 2
JoshFolgado–BusinessEnterpriseArchitect

21. Virtualization
Hosted VMMs
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 Structure
• Hybrid between Type1 and Type2
• Core VMM executes directly on hardware
• I/O services provided by code running on Host
OS
 Goals
• Improve performance overall
• leverages I/O device support on the Host OS
 Disadvantages
• Incurs overhead on I/O operations
• Lacks performance isolation and
performance guarantees
Example: VMware (Workstation)
JoshFolgado–BusinessEnterpriseArchitect

22. Virtualization
Whole-System VMMs
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 Guest OS ISA differs from Host OS ISA
 Requires full emulation of Guest OS and its
applications
Example: VirtualPC
JoshFolgado–BusinessEnterpriseArchitect

23. Virtualization
Strategies
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 De-privileging
• VMM emulates the effect on system/hardware
resources of privileged instructions whose
execution traps into the VMM
• aka trap-and-emulate
• Typically achieved by running Guest OS at a
lower hardware priority level than the VMM
• Problematic on some architectures where
privileged instructions do not trap when executed
at deprivileged priority
 Primary/shadow structures
• VMM maintains “shadow” copies of critical
structures whose “primary” versions are
manipulated by the Guest OS
• e.g., page tables
• Primary copies needed to insure correct
environment visible to Guest OS
 Memory traces
• Controlling access to memory so that the shadow
and primary structure remain coherent
• Common strategy: write-protect primary copies
so that update operations cause page faults
which can be caught, interpreted, and emulated
resource
vmm
privileged
instruction
trap
Guest OS
resource
emulate change
change
JoshFolgado–BusinessEnterpriseArchitect

24. Virtualization
Memory Management
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 Isolation/protection of
Guest OS address
spaces
 Efficient MM address
translation
VMM
machine
VMM Guest OS
“shadow” page tables page tables
process
virtual
OS
physical
entity
address space
JoshFolgado–BusinessEnterpriseArchitect

25. The Virtual Server Concept
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Virtual Machine Monitor (VMM) layer between
Guest OS and hardware
JoshFolgado–BusinessEnterpriseArchitect

26. The Virtual Server Concept
Virtual servers can still be referred to by their
function i.e. File Server, 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
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JoshFolgado–BusinessEnterpriseArchitect

27. The Virtual Server Concept
Virtual servers can be easily scaled out
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
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JoshFolgado–BusinessEnterpriseArchitect

28. 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)
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JoshFolgado–BusinessEnterpriseArchitect

29. Virtualization Status
Offerings from many companies
e.g. VMware, Microsoft, Sun, ...
Hardware support
 Fits well with the move to 64 bit (very large memories)
multi-core (concurrency) processors.
 Intel VT (Virtualization Technology) provides hardware to
support the Virtual Machine Monitor layer
Virtualization is now a well-established technology
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JoshFolgado–BusinessEnterpriseArchitect

30. So what about Cloud Computing?
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JoshFolgado–BusinessEnterpriseArchitect

31. Suppose you are Forbes.com
You offer on-line real
time stock market data
Why pay for capacity
weekends, overnight?
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9 AM - 5 PM,
M-F
ALL OTHER
TIMES
Rate of
Server
Accesses
JoshFolgado–BusinessEnterpriseArchitect

32. Forbes' Solution
Host the web site in Amazon's EC2 Elastic Compute
Cloud
Provision new servers every day and de-provision them
every night
Pay just $0.10* per server per hour
* more for higher capacity servers
Let Amazon worry about the hardware!
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JoshFolgado–BusinessEnterpriseArchitect

33. Cloud Computing takes
Virtualization to the next step
You don’t have to own the hardware
You “rent” it as needed from a cloud
There are public clouds
e.g. Amazon EC2, and now many others
(Microsoft, IBM, Sun, and others ...)
A company can create a private one
With more control over security, etc. 33
JoshFolgado–BusinessEnterpriseArchitect

34. Goal 1 – Cost Control
Cost
• Many systems have variable demands
• Batch processing (e.g. New York Times)
• Web sites with peaks (e.g. Forbes)
• Startups with unknown demand (e.g. the Cash
for Clunkers program)
• Reduce risk
• Don't need to buy hardware until you need it
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JoshFolgado–BusinessEnterpriseArchitect

35. Goal 2 - Business Agility
More than scalability - elasticity!
• Ely Lilly in rapidly changing health care business
• Used to take 3 - 4 months to give a department a
server cluster, then they would hoard it!
• Using EC2, about 5 minutes!
• And they give it back when they are done
Scaling back is as important as scaling up
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JoshFolgado–BusinessEnterpriseArchitect

36. Goal 3 - Stick to Your Business
Most companies don't WANT to do system
administration
• Forbes says:
• We are is a publishing company, not a software
company
But beware:
• Do you really save much on sys admin?
• You don't have the hardware, but you still need
to manage the OS!
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JoshFolgado–BusinessEnterpriseArchitect

37. How Cloud Computing Works
Various providers let you create virtual servers
• Set up an account, as easily as using a credit card
You create virtual servers ("Virtualization")
• Choose the OS and software each "instance" will have
• It will run on a large server farm located somewhere
• You can instantiate more on a few minutes' notice
• You can shut down instances in a minute or so
They send you a bill for what you use
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JoshFolgado–BusinessEnterpriseArchitect

38. Cloud Computing Status
Rapidly becoming a mainstream practice
Numerous providers
• Amazon EC2 imitators ...
• Just about every major industry name
• IBM, Sun, Microsoft, ...
Major buzz at industry meetings
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JoshFolgado–BusinessEnterpriseArchitect