Tài liệu Module 1: Introduction to Windows Clustering docx

Introducing Microsoft Windows 2000 Clustering • This topic provides a brief overview of each of the Windows 2000 Advanced Server clustering technologies.. Identifying the Application and

Contents

Overview 1

Introducing Application Architecture 4

Identifying Availability and Scalability

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Program Manager: Don Thompson

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Instructional Designers: April Andrien, Priscilla Johnston, Diana Jahrling

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After completing this module, students will be able to:

Define clustering features

Define application architecture

Identify clustering technologies that can improve availability and scalability

in an enterprise system

Identify the available Microsoft clustering technologies

Identify the similarities and appropriate use of the clustering technologies

Identify the applications and services that can benefit from clustering technologies

Materials and Preparation

This section provides the materials and preparation tasks that you need to teach this module

Required Materials

To teach this module, you need the Microsoft PowerPoint® file 2087A.01.ppt

Preparation Tasks

To prepare for this module, you should:

Read all of the materials for this module

Complete the labs

Study the review questions and prepare alternative answers to discuss

Anticipate questions that students may ask Write out the questions and provide the answers

Presentation:

90 Minutes

Module Strategy

Use the following strategy to present this module:

Defining Clustering Features

• Review and discuss each of the clustering feature definitions and clarify any points of confusion for the students

• Be prepared to discuss the Mean Time Between Failure concepts that are presented in the topic Comparing Reliability and Availability A white board representation of hardware dependencies would be appropriate

Introducing Application Architecture

• This topic is an overview to the application architecture model

Find out how knowledgeable the students are in each of the technologies and identify whether students require more background information on a given technology

• Emphasize that the Application Architecture model is generic in nature Organizations typically customize the model to suit their unique situations Avoid spending time discussing implementation and management philosophies

• Be prepared to expand each level of the slide graphic and discuss the application architecture of each

Identifying Availability and Scalability Solutions

• This topic describes how clustering can provide solutions for scalability and availability issues

• Discuss the importance of completing a risk assessment to determine if clustering is a viable solution

• Emphasize the importance of providing and maintaining a high levels of availability and scalability for applications and data

• Use the example provided to clearly demonstrate the concept of measuring high availability

Introducing Microsoft Windows 2000 Clustering

• This topic provides a brief overview of each of the Windows 2000 Advanced Server clustering technologies

• Emphasize the feature sets for each of the clustering technologies

• Demonstrate where each technology can fit into the network architecture

Comparing Network Load Balancing to Cluster Service

• This topic describes the benefits of both Cluster Service and Network Load Balancing

• Briefly review the benefits for each technology and how that applies to several different business scenarios

Identifying the Application and Service Environments

• This topic is an overview of the applications and services that are compatible with a clustering solution

• Emphasize the importance of identifying which applications and services are appropriate for a clustering solution

Discussion: Evaluating Business Scenarios

• Review Scenario one and Scenario two with the students and have them complete both scenarios

• Although Scenario one is the simpler of the two scenarios, explain to the students that they are expected to recognize where problems exist in the scenario

• Scenario two is much more complex Explain to the students that they are expected to consider:

• Use of Network Load Balancing, Component Load Balancing and Cluster Service in both scenarios

• How applications and development processes will influence the possible solutions

• How fault tolerance would be implemented within the applications used

• Students may not have experience at this level Be expected to lead the discussion

Overview

Defining Clustering Features

Introducing Application Architecture

Identifying Availability and Scalability Requirements

Introducing Microsoft Windows 2000 Clustering

Comparing Network Load Balancing to Cluster Service

Identifying the Application and Service Environments

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As your organization’s business needs grow, you must be able to expand your organization’s system capacity economically, avoid single points of failure and quickly restore failed services and applications for users Microsoft®

Windows® 2000 Clustering enables you to provide availability, scalability, and load balancing for applications and services

This module describes the central concepts of Cluster service and Network Load Balancing service, by providing a brief background of clustering technologies and explaining what Windows 2000 Clustering provides

In this course, a cluster is defined as a group of independent computers working

together as a single system Microsoft clustering technologies provide the functionality that is required to enable you to configure multiple computers as a single logical system In this module, you will learn the key benefits of

Microsoft Windows 2000 Clustering and how they apply within single and multiple tier application architectures

After completing this module, you will be able to:

Define clustering features

Define application architectures

Identify clustering technologies that can improve availability and scalability

in an enterprise system

Identify the available Microsoft clustering technologies

Identify the similarities and appropriate use of the clustering technologies

Identify the applications and services that can benefit from clustering technologies

In this module, you will learn

the central concepts of

Windows 2000 Clustering

technologies

Defining Clustering Features

High Availability and Fault Tolerance

Manageability

Scalability

Comparing Reliability and Availability

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A working knowledge of a clustering solution begins with the definitions of clustering features

High Availability and Fault Tolerance

A system that is available whenever users want to use it and provides service that meets a defined organizational standard is considered to have high availability

When a system or component in a cluster fails, the cluster software responds by reallocating the resources from the failed system to the remaining systems in the cluster, thereby ensuring that the system is providing high availability to client/server applications and services

Throughout this process, client communications with applications or services usually continue with minimal interruption in service and Clustering provides a single, virtual image of the server to clients Most client software applications will automatically recover from the broken connections with little or no interruption to the user

A fault tolerant solution is one that addresses performance by offering free, nonstop availability, usually by keeping a backup of the primary system This backup system remains idle and unused until a failure occurs, which makes this an expensive solution

error-Manageability

Although manageability is not a key feature of clustering technologies, it allows system administrators to perform all of the necessary functions of maintaining the system by providing a single point of control Administrators can access a single point of control remotely or run tools that provide a view of the system members, which allows control of the servers as a single logical entity

Cluster service begins by

learning the definitions of

clustering features

Delivery Tip

Emphasize the difference

between fault tolerance and

high availability High

availability does not ensure

that a system is fault

tolerant

Carefully review the Mean

Time Between Failure, use

the example provided to

demonstrate the concept

Be prepared for questions

from the students regarding

geographical high

availability For example,

there are two data centers,

one in Houston, Texas and

the other in San Ramon,

California The students

might want to know how

availability is maintained

between the two data

centers if a catastrophic

event occurred

Scalability

A system can be scaled up, scaled out, or scaled down

Scaling up Achieved by adding more resources, such as memory,

processors, and disk drives to a system

Scaling out Achieved by adding additional computers to deliver high

performance when the throughput requirements of an application exceed the capabilities of an individual system

Scaling down Achieved by reducing resources

When the overall load exceeds the capabilities of the systems in a cluster, you may need to add additional systems You will find that clusters are highly scalable; you can add CPU, input/output (I/O) storage, and application resources incrementally to efficiently expand or contract capacity by

implementing one of the three types of scaling architectures

Comparing Reliability and Availability

High availability and high reliability are at times used interchangeably, but when considering complex systems, each can have a different meaning

When designing products, for example a computer motherboard, there is a failure rate defined for each component The reliability number may be expressed as Mean Time Between Failure (MTBF), which shows the measured failure rate based on testing of the individual components

The testing regime is usually a large number of components being tested in a benign environment within their operating parameters, the aggregate run hours without failure are used to ascertain the MTBF Given the reliability figures of all of the components, it is possible to calculate the probability of failure of the motherboard within a given time This MTBF number is a measure of the reliability of the component and recognizes that all components will fail in time For example, disk drives may have an MTBF of 1x106 power hours

A system with high availability is one where you expect that whenever you want to use it, it is available to provide service meeting your defined standard

So a computer system might be expected to be available 24 hours a day, 7 days

a week, 52 weeks a year; in other words, it can never stop working There is a distinct advantage to using high reliability components to build high availability systems, because the probability of a failure is lower However, you can build high availability systems by using unreliable components, provided that you use some fault-tolerant mechanism to maintain operation

Introducing Application Architecture

User Services

Business Services

Data Services

Two-Tier Thin Client

Two-Tier Thin Client Fat Client Two-Tier

Two-Tier Fat Client Three-Tier N-Tier User Interface

Microsoft Win32®

User Interface Microsoft Win32®

User Interface Win32 Most Business Logic

User Interface Win32 Most Business Logic

User Interface Win32 Browser

User Interface Win32 Browser

User Interface Win32 Browser DHTML, XML

User Interface Win32 Browser DHTML, XML Business Logic

COM Objects

Business Logic COM Objects User Interface ASP

Business Logic COM Objects

User Interface ASP Business Logic COM Objects Storage

RDBMS All Business Logic (SP)

Storage RDBMS All Business Logic (SP)

Storage RDBMS Min Business Logic (SP)

Storage RDBMS Min Business Logic (SP)

Storage RDBMS Min Business Logic (SP)

Storage RDBMS Min Business Logic (SP)

Storage RDBMS Min Business Logic (SP)

Storage RDBMS Min Business Logic (SP)

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The application architecture defines how pieces of the application interact with each other, and what functionality each piece is responsible for performing There are three main classes of application architecture that can be

characterized by the number of layers between the user and the data

The three types of application architecture are two-tier, three-tier and n-tier, where n can be three or more The table demonstrates the user, business, and

data services layers in each of the application architectures One of the benefits

of a three-tier or n-tier model is that applications are divided cleanly into

presentation, business logic, and data layers This division results in enhanced scalability and manageability, which can be improved by Windows Clustering technologies

Two-Tier

In a thin client, two-tiered model, the business logic is server-based and typically consists of stored procedures in the database server You must install client code on every client accessing the application; the client code is responsible for the user interface only

In a fat client, two-tiered model, you must install client code on every client accessing the application; the client code is responsible for the user interface and most of the business logic The database can still have stored procedures, but the requirements for these procedures are reduced This model requires that more resources are available on the client

Three-Tier

In a three-tiered model, the business layer or application layer lies between data and client This layer is responsible for both the application's business logic and the overall management of business transactions Often the application layer will utilize object technologies

defines how pieces of the

application interact with

each other, and what

functionality each piece is

responsible for performing

Delivery Tip

Be prepared to expand all

three tiers of the model and

explain the applications and

services in each of them

Key Point

One of the benefits of a

three-tier or n-tier model is

that applications are divided

cleanly into presentation,

business logic, and data

layers; the result will be

enhanced scalability and

manageability

N-Tier

In an n-tier model, the user-services tier or first tier handles presentation of

information and interaction with the users Some sources refer to this first tier

as presentation services, because some of the services that are performed in the middle or business services tier of an application, such as authenticating users, are also user services

The business-services tier provides most of an application's functionality This tier handles the bulk of application-specific processing and enforces an application's business rules Business logic built into custom components bridges the client environments and the data-services tier

The data-services tier in an n-tier application can consist of data residing in

several different kinds of stores

Although this split is conceptual, it can be mirrored in a real-world scenario by implementing the data tier on a number of computers running a high

performance database, such as Microsoft SQL Server™; implementing the business tier on a set of separate computers; and implementing the presentation

tier on yet another set of computers When you complete the n-tier

implementation, you achieve redundancy and if a single computer fails, the applications and services are available on the other computers This environment also addresses the need for scalability by allowing users to incorporate different hardware

Application Architecture Development Strategies

Developing applications for a Microsoft platform will typically use Microsoft development tools and strategies Current applications use the Windows Distributed interNet Application Architecture (Windows DNA) strategies for development and future development extend this using Microsoft NET Enterprise Servers

Windows DNA

The Windows DNA model distributes an application in several layers, called tiers, which often reside physically on different machines, emphasizing logical distribution

Microsoft developed Windows DNA as a way to fully integrate the Web with

the n-tier model of development Windows DNA defines a framework for

delivering solutions that meet the demanding requirements of corporate computing, the Internet, intranets, and global electronic commerce, while reducing overall development and deployment costs

Windows DNA architecture employs standard Windows-based services to address the requirements of each tier in the multitiered solution: user interface and navigation, business logic, and data storage

Microsoft NET

The core services of NET are fulfilled by a set of strategies for the development Internet-based applications These core services include services and development strategies for user identification, data storage, calendar management, messaging, database, and many other services

Identifying Availability and Scalability Requirements

Assessing Risks

Scalability

High Availability

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As a system administrator planning to expand your system’s capacity, you may

be required to make commitments to expensive high-end servers that provide space for additional CPUs, drives, and memory By using a clustering technology solution, you will be able to incrementally add smaller, standard systems as needed to meet overall processing power requirements

Clustering solutions are ideal when you need more system processing power or high availability For example, you would consider using a clustering solution for an Internet server-based program supporting mission-critical applications, such as financial transactions, database access, corporate intranets, and other key functions that must run 24 hours a day, 7 days a week

Implementing a clustering solution makes it possible for you to share a computing load over several computer systems, without the users needing to know that more than one computer is involved If any component in the system (hardware or software) fails, the user will not lose access to the service or application

Topic Objective

To identify how clustering is

a solution for availability and

scalability issues

Lead-in

As a system administrator

planning to expand your

system’s capacity, you may

be required to make

commitments to expensive

high-end servers that

provide space for additional

CPUs, drives, and memory

Delivery Tip

This topic is meant to

provide just an overview of

scalability and high

availability Advise the

students that each of these

features will be covered in

much more detail in the

Server Cluster and Network

Load Balancing cluster

modules

Power

Performing a Risk Audit

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A risk audit helps you to identify system risk; it also helps to determine if clustering is an appropriate solution to reduce the risk More specifically it helps to identify where you can use clustering to eliminate single points of failure and maintain availability

Identifying Risks

When you identify risks, you identify the possible failures that can interrupt

access to resources A single point of failure is any component in your

environment that would block data or applications if it failed A single point of failure can be caused by hardware, software, or external dependencies, such as power supplied by a utility company and dedicated wide area network (WAN) lines

In general, you provide improved reliability when you minimize the number of single points of failure in your environment Maximum reliability is provided

by mechanisms that maintain service when a failure occurs by providing fault tolerance

Topic Objective

To identify possible points of

failure before implementing

a clustering solution

Lead-in

A risk audit identifies

network risk and helps to

determine if clustering is an

appropriate solution to

reduce risk

Delivery Tip

Emphasize the importance

of identifying single points of

failure while doing a risk

audit prior to installing the

Network Load Balancing

driver

Performing a Risk Audit

The following table lists some of the more commonly encountered points of failure

Point of failure Cluster service solution Possible other solutions

Network component, such

CPU, memory, or network card

Failover process of taking resources offline on one node and bringing them back online on another node

None

Independent Disks (RAID)

Sever software, such as the operating system, a service, or an application

Failover None

Clustering cannot eliminate all possible points of failure It is designed to protect availability to data but it cannot protect the data itself Therefore, it is still important to have a backup strategy

Note

Scalability

Enhanced Symmetric Multiprocessing

Cluster Service

Network Load Balancing

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Microsoft Windows 2000 Advanced Server provides integrated system scalability through enhanced symmetric multiprocessing (SMP), in addition to the two Windows Clustering technologies, Cluster service and Network Load Balancing service

Combined with relatively inexpensive computer hardware, Windows 2000 Advanced Server gives organizations powerful and scalable alternatives to more expensive proprietary solutions

Enhanced Symmetric Multiprocessing Scalability

SMP is a technology that allows software to use multiple processors on a single

server to improve performance, a concept known as hardware scaling, or scaling up

Windows 2000 Advanced Server supports up to 8-way SMP Improvements in the implementation of the SMP code allow for improved scaling linearity, making Windows 2000 Advanced Server an even more powerful platform for business-critical applications, databases, and Web services In an SMP system, several processors share a global memory and I/O subsystem

At the hardware level, the major drawback to SMP systems is that they encounter physical limitations in bus and memory speed that are expensive to overcome As microprocessor speeds increase, shared memory multiprocessors become increasingly expensive There are large cost differences as customers increase their systems from one processor to 2 to 4 processors, and especially when implementing more than 8 processors

Cluster Service

Cluster service is a feature of Windows 2000 Advanced Server that allows a pair of independent servers, referred to as nodes, to be managed as a single entity The objective of Cluster service is to provide high levels of availability and scalability for applications and data

Topic Objective

To identify the clustering

technologies that provide

scalability

Lead-in

Microsoft Windows 2000

Advanced Server provides

integrated system scalability

Network Load Balancing

Network Load Balancing service enables organizations to cluster up to 32 servers running Windows 2000 Advanced Server to evenly distribute incoming traffic while also monitoring servers and the network The dual benefits of simple, incremental scalability combined with high-availability make Network Load Balancing service ideal for use with business-critical e-commerce, Internet Service Provider hosting, and Terminal Services applications

Network Load Balancing service introduces the concept of software scaling; or scaling out, where system administrators can add capacity to their server farms

by simply plugging in additional Network Load Balancing service-configured servers as needed

High Availability

Measuring High Availability

Cluster Service

Network Load Balancing

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Windows 2000 Advanced Server provides system services for server clustering

as a standard feature of the product The objective of clustering is to provide very high levels of application and data availability

Availability refers to the percentage of time that a system is available for the users Availability is increased by improving reliability and by reducing the amount of time that a system is down for various reasons, such as planned maintenance or recovery from failure

Measuring High Availability

High availability is a measure of the time during which clients can successfully use a resource, application, or system within design specifications

Availability is normally expressed as a percentage For example, a computer system that is required on a 24x365 basis that is unavailable for 24 hours would have an availability percentage of 99.62% To achieve 99.99% availability this system can only be unavailable for 53 minutes per year To achieve 99.999% availability this system can only be unavailable for 5.3 minutes a year

A computer system with high availability will optimally provide continuous service without interruptions that are caused by software or hardware failures

Topic Objective

To identify the clustering

technologies that provide

high availability

Lead-in

Windows 2000 Advanced

Server provides system

services for server

clustering as a standard

feature of the product The

objective of clustering is to

provide very high levels of

application and data

Ensure that the students

understand that high

availability does not imply

fault tolerance