Virtualization and Cloud Computing

By Josh Folgado

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Client Endpoints

Devices

Public

End Users

Management

OS / Apps / Data

Infrastructure and Services

On-

Prem

ise

Off-

Prem

ise

Traditional IT Environment

3 Source: 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

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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

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The Traditional Server Concept

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Web Server

Windows

IIS

App Server

Linux

Glassfish

DB Server

Linux

MySQL

Email

Windows

Exchange

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And if something goes wrong ...

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Web Server

Windows

IIS

App Server

DOWN!

***

DB Server

Linux

MySQL

Email

Windows

Exchange

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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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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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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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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

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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

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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

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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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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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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.

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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

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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)

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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

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Virtualization Desing Space – (Level vs. ISA)

19 Variety of techniques and approaches available Critical technology space highlighted

API interface ABI interface

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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

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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)

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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

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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

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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

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The Virtual Server Concept

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Virtual Machine Monitor (VMM) layer between Guest OS and hardware

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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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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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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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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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So what about Cloud Computing?

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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

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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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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.

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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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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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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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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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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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