Eric Bauer, Randee Adams, Daniel Eustace

Beyond Redundancy (eBook, ePUB)

How Geographic Redundancy Can Improve Service Availability and Reliability of Computer-Based Systems

• Format: ePub

Produktbeschreibung

While geographic redundancy can obviously be a huge benefit for disaster recovery, it is far less obvious what benefit is feasible and likely for more typical non-catastrophic hardware, software, and human failures. Georedundancy and Service Availability provides both a theoretical and practical treatment of the feasible and likely benefits of geographic redundancy for both service availability and service reliability. The text provides network/system planners, IS/IT operations folks, system architects, system engineers, developers, testers, and other industry practitioners with a general discussion about the capital expense/operating expense tradeoff that frames system redundancy and georedundancy.

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Produktdetails

• Verlag: John Wiley & Sons
• Seitenzahl: 330
• Erscheinungstermin: 23. September 2011
• Englisch
• ISBN-13: 9781118104934
• Artikelnr.: 37339040

Autorenporträt

Eric Bauer is Reliability Engineering Manager in the IMS Solutions Organization of Alcatel-Lucent, where he focuses on reliability of Alcatel-Lucent's IMS solution and the network elements that comprise the IMS solution. He has written Design for Reliability: Information and Computer-Based Systems and Practical System Reliability. Randee Adams is a Consulting Member of Technical Staff in the Applications Group of Alcatel-Lucent. Currently, she is focusing on reliability for Alcatel-Lucent's software applications. Daniel Eustace is a Distinguished Member of Technical Staff in the IMS Solutions Organization of Alcatel-Lucent. Currently, he is a solution architect focusing on reliability, key quality indicators, geographical redundancy, and call processing.

Inhaltsangabe

Figures xv Tables xix Equations xxi Preface and Acknowledgments xxiii
Audience xxiv Organization xxiv Acknowledgments xxvi PART 1 BASICS 1 1
SERVICE, RISK, AND BUSINESS CONTINUITY 3 1.1 Service Criticality and
Availability Expectations 3 1.2 The Eight-Ingredient Model 4 1.3
Catastrophic Failures and Geographic Redundancy 7 1.4 Geographically
Separated Recovery Site 11 1.5 Managing Risk 12 1.6 Business Continuity
Planning 14 1.7 Disaster Recovery Planning 15 1.8 Human Factors 17 1.9
Recovery Objectives 17 1.10 Disaster Recovery Strategies 18 2 SERVICE
AVAILABILITY AND SERVICE RELIABILITY 20 2.1 Availability and Reliability 20
2.2 Measuring Service Availability 25 2.3 Measuring Service Reliability 33
PART 2 MODELING AND ANALYSIS OF REDUNDANCY 35 3 UNDERSTANDING REDUNDANCY 37
3.1 Types of Redundancy 37 3.2 Modeling Availability of Internal Redundancy
44 3.3 Evaluating High-Availability Mechanisms 52 4 OVERVIEW OF EXTERNAL
REDUNDANCY 59 4.1 Generic External Redundancy Model 59 4.2 Technical
Distinctions between Georedundancy and Co-Located Redundancy 74 4.3 Manual
Graceful Switchover and Switchback 75 5 EXTERNAL REDUNDANCY STRATEGY
OPTIONS 77 5.1 Redundancy Strategies 77 5.2 Data Recovery Strategies 79 5.3
External Recovery Strategies 80 5.4 Manually Controlled Recovery 81 5.5
System-Driven Recovery 83 5.6 Client-Initiated Recovery 85 6 MODELING
SERVICE AVAILABILITY WITH EXTERNAL SYSTEM REDUNDANCY 98 6.1 The Simplistic
Answer 98 6.2 Framing Service Availability of Standalone Systems 99 6.3
Generic Markov Availability Model of Georedundant Recovery 103 6.4 Solving
the Generic Georedundancy Model 115 6.5 Practical Modeling of Georedundancy
121 6.6 Estimating Availability Benefit for Planned Activities 130 6.7
Estimating Availability Benefit for Disasters 131 7 UNDERSTANDING RECOVERY
TIMING PARAMETERS 133 7.1 Detecting Implicit Failures 134 7.2 Understanding
and Optimizing RTO 141 8 CASE STUDY OF CLIENT-INITIATED RECOVERY 147 8.1
Overview of DNS 147 8.2 Mapping DNS onto Practical Client-Initiated
Recovery Model 148 8.3 Estimating Input Parameters 154 8.4 Predicted
Results 165 8.5 Discussion of Predicted Results 172 9 SOLUTION AND CLUSTER
RECOVERY 174 9.1 Understanding Solutions 174 9.2 Estimating Solution
Availability 177 9.3 Cluster versus Element Recovery 179 9.4 Element
Failure and Cluster Recovery Case Study 182 9.5 Comparing Element and
Cluster Recovery 186 9.6 Modeling Cluster Recovery 187 PART 3
RECOMMENDATIONS 201 10 GEOREDUNDANCY STRATEGY 203 10.1 Why Support Multiple
Sites? 203 10.2 Recovery Realms 204 10.3 Recovery Strategies 206 10.4
Limp-Along Architectures 207 10.5 Site Redundancy Options 208 10.6
Virtualization, Cloud Computing, and Standby Sites 216 10.7 Recommended
Design Methodology 217 11 MAXIMIZING SERVICE AVAILABILITY VIA GEOREDUNDANCY
219 11.1 Theoretically Optimal External Redundancy 219 11.2 Practically
Optimal Recovery Strategies 220 11.3 Other Considerations 228 12
GEOREDUNDANCY REQUIREMENTS 230 12.1 Internal Redundancy Requirements 230
12.2 External Redundancy Requirements 233 12.3 Manually Controlled
Redundancy Requirements 235 12.4 Automatic External Recovery Requirements
237 12.5 Operational Requirements 242 13 GEOREDUNDANCY TESTING 243 13.1
Georedundancy Testing Strategy 243 13.2 Test Cases for External Redundancy
246 13.3 Verifying Georedundancy Requirements 247 13.4 Summary 254 14
SOLUTION GEOREDUNDANCY CASE STUDY 256 14.1 The Hypothetical Solution 256
14.2 Standalone Solution Analysis 259 14.3 Georedundant Solution Analysis
263 14.4 Availability of the Georedundant Solution 269 14.5 Requirements of
Hypothetical Solution 269 14.6 Testing of Hypothetical Solution 277 Summary
285 Appendix: Markov Modeling of Service Availability 292 Acronyms 296
References 298 About the Authors 300 Index 302