Practical Load Balancing

Practical Load

_Balancing

Ride the Performance

_Tiger

Illtil

Peter

_Membrey

David Hows

Eelco

_Plugge

Contents

About the Authors xvii

About the Technical Reviewers xviii

Special

Thanks to serverlove xix

Acknowledgments

xx

Preface xxi

Chapter

1: Introduction 1

The Problem 1

The Solution 2

What Is Load

_Balancing?

3

Load _Balancing,Old_Style 3

Load Balancing,NewStyle 3

Scaling Up 3

ScalingOut 4

Load

_Balancing,

_Finally

4

What Makes the Web Tick? 4

Caching: WarpDrive for Your Web Site 5

Load _Balancingwith DNS 5

Content_DeliveryNetworks 5

Proper PlanningPreventsPrettyPoor Performance 6

The Essentials 6

HTTP LoadBalancing 6 Load_Balancing YourDatabase 6

CONTENTS

Load_BalancingYour Network Connection 7

SSL Load_Balancing 7

Clusteringfor_{High Availability 7}

Load_Balancingin the Cloud 7

IPv6:_{Implementation} and_Concepts 7

Where To Go Next 8

Summary

8

Chapter

2: How Web Sites Work 9

Let the Games Commence! 10

ComingfromaNon-ITBackground 10

KickingOff the Process 10

Finding theSite with DNS 11

Connectingto the Server_(Finally!) 11

On the Server itself 12 Talkingto the Database 12

QuickLook at_Caching 13 Backto theClient 13

Taking

a Closer Look ₁₃

The Network ₁₄

TCP ₁₄

DNS 16

Speed, Bandwidth,and _Latency 17

Network_{Summary 20}

HTML and the Web 20

HTML ₂₁

Whyis Text-Based_{Important? 21}

Why is_{LinkingImportant? 22}

HTML_{Summary 23}

«CONTENTS

Web Content 24

StaticContent 25

DynamicContent 25

CreatingDynamicContent 25

Web_{Content Summary} 27

Databases: The Weakest Link 27

Summary

27

Chapter

3: Content

_Caching:

_Keeping

the Load

_Light

29

What IsaCache? 30

Whistle

_Stop

Tour 30

Browser-based_Caching 31 Web Accelerators 31

Web Proxies 32

TransparentWeb Proxies 33

Edge-based Caching 35

Platform_Caching 35

Application Caching 36

Database_Caching 37

Justthe_Beginning 37

Caching

Theory:

Why

Is ItsoHard? 37

HTTP1.0_{CachingSupport} 38

HTTP1.1 Enhanced_CachingSupport 38

The Solution 39

Caching Isn'tasEasyasItLooks 40

Web Proxies 40

The_SquidProxyServer 41

GettingStarted 41

Troubleshooting 43

mCONTENTS

TransparentProxies 43

What's _Going On 44

Gettinga_HelpingHand 45

Squid,the SwissArmyKnife ofProxies 46

Edge-based Caching: Introducing

Varnish 46

Sane _CachingbyDefault 47

InstallingVarnish 48

Getting Upand_Running 49

CustomizingVarnish 51

Summary

51

Chapter

4: DNS Load _{Balancing 53}

DNS Details 53

The IPAddress 53

TheProblem 54

The Solution 54

Taking aStepBack 55

DNS in

_Depth

₅₅

QueryingYourself 56

Advanced DNS Queries 57

DNS

_Caching

₅₈

QueryingyourDNS Cache 59

DNSCache in Linux 60

The RealStuff 60

BIND9 61

DNS DB Header 62

DNSDatabase Entries 63

LoadingyourDB 65

Checkingthe_Config 65

CONTENTS

Common Issues 66

TestingyourDNS 66

DNS Load

_Balancing

67

Advantagesof DNSLoadBalancing 67

Issues with DNSLoadBalancing 68

Summary

69

Chapter

5: Content

_Delivery

Networks 71

Choosing

aCDN Provider 72

Getting

Started with

_Rackspace

72

Adding

Content to Your CDN Account 74

The

_Rackspace

Cloud Files API 77

Integratingthe API into PHP 77

Authenticating with YourAPI _Key 78

Connecting and Disconnecting 78

Workingwith Containers 79

Workingwith Files 85

OtherUseful Functions 91

Summary

92

Chapter

6:

_Planning

for Performance and

_{Reliability...}

...93

yoU

MAke Dinner In TiME 94

yoU 94

MAke 97

Dinner 97

In 98

TiME 100

The_Importanceof_Planning 101

S_CONTENTS

Backups

103

WhyBackupsAresoImportant ₁₀₃

There MayBe Trouble Ahead ₁₀₃

Automation isaMust ₁₀₄

Tactical Backups 105

StrategicBackups 105

Incrementalvs. Full ₁₀₆

Please, PleasePerform Test Restores! ₁₀₆

Summary

106

Chapter

7: Load

_Balancing

Basics 109

What Is Load

_Balancing?

₁₀₉

What

_Computing

Resources AreAvailable? 110

Processor_{(CPU) 110}

Memory(RAM) 111

CheckingPerformance ofCPU_{and RAM with top 111}

Network ₁₁₃

Storage (Disk) 114

Load

_Balancing

in Practice ₁₁₄

Guiding

Principles

115

UnderstandYour_{System 115}

Planning 116

Monitoringand_{Testing 116}

Summary

116

Chapter

8: Load

_Balancing

Your Web Site 117

Measuring

Web Server Performance ₁₁₇

Accelerating Apache

HTTP ₁₂₀

Disabling UnneededModules ₁₂₀

aCONTENTS

UsingCompression 121

FollowSymLinksand_{SymLinkslfOwnerMatch} 123

Accelerating

nginx

123

worker_processesandworker_cpu_affinity 124

Gzip Compression 125

Load

_Balancing

Your Web Server 126

The_Setup 127

Preparingthe Server 128

Preparingthe Workers 130

TestingtheLoad Balancer 131

Best of Both Worlds 132

Summary

134

Chapter

9: Load

_Balancing

Your Database 135

Setting

up the

MySQL

Cluster 135

Installingthe_ManagementSoftware 137

Configuringthe _ManagementSoftware 138

Preparingthe Cluster'sDataNodes 140

Installingthe _MySQLServer and NOB Daemon 141

Configuringthe NDB Daemon 142

StartingtheCluster Node's Services 143

Updating MySQL'sRoot User 144

TestingtheInstallation 145

Applying

Load

_Balancing

147

TheSetup 148

Settingupthe Load Balancer 148

Preparingthe Workers 150

Testingthe Load Balancer 150

Summary

151

CONTENTS

Chapter

10: Network Load

_Balancing

153

Sharing

the Workload 153

TCP/IP ₁₅₄

TCP 154

IP ₁₅₅

Routing

155

The Load Balancer 157

IPVS ₁₆₀

IPVS_{Scheduling 160}

IPVS Installation onUbuntu ₁₆₂

IPVSInstallationonCentos 163

IPVSADM ₁₆₄

Expanding

IPVS ₁₆₆

Advanced IPVS 167

Changing Scheduling Algorithm 167

Assigning WeightValues 168

Protocol and_MultipleVirtual Servers ₁₇₀ Another IP Address 171

Making

It Stick ₁₇₃

Summary

174

Chapter

11: SSL Load

_Balancing

₁₇₅

Whatare SSLandTLS? 175

Public-Key

Cryptography

176

Trust and Certificate Authorities 177

TLS

_Encryption

₁₇₈

TLS Load

_Balancing

178

CONTENTS

Configuring

SSL onYour WebServer 179

Apache 181

Nginx 182

SSLAcceleration 182

Apache 183

Nginx

183

SSL Termination 183

Configuring Nginx

184

Testing

the SSL 185

Further

_{Configurations}

187

Engine 187

Caching 188

Protocols 189

SpecificCiphers 189

LVS and Your SSL Terminator 191

Integrated

Load Balancer/SSL Terminator 192

Summary

192

Chapter

12:

_Clustering

for

_{High Availability}

193

High

Availability

194

Single

Point of Failure 195

Clustering

197

IPVS Failover 198

Install with Ubuntu 199

Install with Centos 200

Configure 200

CommonConfigProblems 203

ConfirmingYour_System 204

ilCONTENTS

Testing

206

Web Server

_Specifics

207

Ubuntu 207

Centos 207

Advanced

Config Options

208

ha.cf 208

Idirectord.cf 208

Web Server 209

Summary

209

Chapter

13: Load

_Balancing

in the Cloud 211

Cloud

_Computing

211

Virilization 212

Hypervisor 212

Virtualized Resources 215

Managing

Virtual Resources 216

Balancing 217

Overprovisioning 219

Planning 219

Cloud

_Elasticity

220

Working

withaCloud Server 221

Summary

224

Chapter

14: IPv6:

_Implications

and

_Concepts

225

IPv6 225

Hexadecimal Notation 225

mCONTENTS

IPv4 Exhaustion 226

Approach

to IPv6 227

Advantages

of IPv6 227

Implementation

228

Internet Connection 229

DNS 230

Operating

System

230

Networking

230

Single GatewayNetwork 231

Dual Network 231

Application Support

231

Apache 231

Nginx 232

Varnish Cache 232

Memcached 233

IPVS 233

Ldirectord 234

Heartbeat 234

Summary

234

Chapter

15: Where to Go Next 235

Recap 236

Monitoring

236

Security

237

AccessControl 238

Views 238

Common_ExploitPrevention 239

*CONTENTS

Operating

System

Performance 240

CompileYourself 240

CutDown 240

High-PerformanceOS 241

Planning 241

Summary

241

Index.. ....243