Reliability and Availability of Cloud Computing

Figures xvii
<p>Tables xxi</p>
<p>Equations xxiii</p>
<p>Introduction xxv</p>
<p>I BASICS 1</p>
<p>1 CLOUD COMPUTING 3</p>
<p>1.1 Essential Cloud Characteristics 4</p>
<p>1.2 Common Cloud Characteristics 6</p>
<p>1.3 But What, Exactly, Is Cloud Computing? 7</p>
<p>1.4 Service Models 9</p>
<p>1.5 Cloud Deployment Models 11</p>
<p>1.6 Roles in Cloud Computing 12</p>
<p>1.7 Benefi ts of Cloud Computing 14</p>
<p>1.8 Risks of Cloud Computing 15</p>
<p>2 VIRTUALIZATION 16</p>
<p>2.1 Background 16</p>
<p>2.2 What Is Virtualization? 17</p>
<p>2.3 Server Virtualization 19</p>
<p>2.4 VM Lifecycle 23</p>
<p>2.5 Reliability and Availability Risks of Virtualization 28</p>
<p>3 SERVICE RELIABILITY AND SERVICE AVAILABILITY 29</p>
<p>3.1 Errors and Failures 30</p>
<p>3.2 Eight–Ingredient Framework 31</p>
<p>3.3 Service Availability 34</p>
<p>3.4 Service Reliability 43</p>
<p>3.5 Service Latency 46</p>
<p>3.6 Redundancy and High Availability 50</p>
<p>3.7 High Availability and Disaster Recovery 56</p>
<p>3.8 Streaming Services 58</p>
<p>3.9 Reliability and Availability Risks of Cloud Computing 62</p>
<p>II ANALYSIS 63</p>
<p>4 ANALYZING CLOUD RELIABILITY AND AVAILABILITY 65</p>
<p>4.1 Expectations for Service Reliability and Availability 65</p>
<p>4.2 Risks of Essential Cloud Characteristics 66</p>
<p>4.3 Impacts of Common Cloud Characteristics 70</p>
<p>4.4 Risks of Service Models 72</p>
<p>4.5 IT Service Management and Availability Risks 74</p>
<p>4.6 Outage Risks by Process Area 80</p>
<p>4.7 Failure Detection Considerations 83</p>
<p>4.8 Risks of Deployment Models 87</p>
<p>4.9 Expectations of IaaS Data Centers 87</p>
<p>5 RELIABILITY ANALYSIS OF VIRTUALIZATION 90</p>
<p>5.1 Reliability Analysis Techniques 90</p>
<p>5.2 Reliability Analysis of Virtualization Techniques 95</p>
<p>5.3 Software Failure Rate Analysis 100</p>
<p>5.4 Recovery Models 101</p>
<p>5.5 Application Architecture Strategies 108</p>
<p>5.6 Availability Modeling of Virtualized Recovery Options 110</p>
<p>6 HARDWARE RELIABILITY, VIRTUALIZATION, AND SERVICE AVAILABILITY 116</p>
<p>6.1 Hardware Downtime Expectations 116</p>
<p>6.2 Hardware Failures 117</p>
<p>6.3 Hardware Failure Rate 119</p>
<p>6.4 Hardware Failure Detection 121</p>
<p>6.5 Hardware Failure Containment 122</p>
<p>6.6 Hardware Failure Mitigation 122</p>
<p>6.7 Mitigating Hardware Failures via Virtualization 124</p>
<p>6.8 Virtualized Networks 127</p>
<p>6.9 MTTR of Virtualized Hardware 129</p>
<p>6.10 Discussion 131</p>
<p>7 CAPACITY AND ELASTICITY 132</p>
<p>7.1 System Load Basics 132</p>
<p>7.2 Overload, Service Reliability, and Service Availability 135</p>
<p>7.3 Traditional Capacity Planning 136</p>
<p>7.4 Cloud and Capacity 137</p>
<p>7.5 Managing Online Capacity 144</p>
<p>7.6 Capacity–Related Service Risks 147</p>
<p>7.7 Capacity Management Risks 153</p>
<p>7.8 Security and Service Availability 157</p>
<p>7.9 Architecting for Elastic Growth and Degrowth 162</p>
<p>8 SERVICE ORCHESTRATION ANALYSIS 164</p>
<p>8.1 Service Orchestration Definition 164</p>
<p>8.2 Policy–Based Management 166</p>
<p>8.3 Cloud Management 168</p>
<p>8.4 Service Orchestration s Role in Risk Mitigation 169</p>
<p>9 GEOGRAPHIC DISTRIBUTION, GEOREDUNDANCY, AND DISASTER RECOVERY 174</p>
<p>9.1 Geographic Distribution versus Georedundancy 175</p>
<p>9.2 Traditional Disaster Recovery 175</p>
<p>9.3 Virtualization and Disaster Recovery 177</p>
<p>9.4 Cloud Computing and Disaster Recovery 178</p>
<p>9.5 Georedundancy Recovery Models 180</p>
<p>9.6 Cloud and Traditional Collateral Benefits of Georedundancy 180</p>
<p>9.7 Discussion 182</p>
<p>III RECOMMENDATIONS 183</p>
<p>10 APPLICATIONS, SOLUTIONS, AND ACCOUNTABILITY 185</p>
<p>10.1 Application Configuration Scenarios 185</p>
<p>10.2 Application Deployment Scenario 187</p>
<p>10.3 System Downtime Budgets 188</p>
<p>10.4 End–to–End Solutions Considerations 197</p>
<p>10.5 Attributability for Service Impairments 201</p>
<p>10.6 Solution Service Measurement 204</p>
<p>10.7 Managing Reliability and Service of Cloud Computing 207</p>
<p>11 RECOMMENDATIONS FOR ARCHITECTING A RELIABLE SYSTEM 209</p>
<p>11.1 Architecting for Virtualization and Cloud 209</p>
<p>11.2 Disaster Recovery 216</p>
<p>11.3 IT Service Management Considerations 217</p>
<p>11.4 Many Distributed Clouds versus Fewer Huge Clouds 224</p>
<p>11.5 Minimizing Hardware–Attributed Downtime 225</p>
<p>11.6 Architectural Optimizations 231</p>
<p>12 DESIGN FOR RELIABILITY OF VIRTUALIZED APPLICATIONS 244</p>
<p>12.1 Design for Reliability 244</p>
<p>12.2 Tailoring DfR for Virtualized Applications 246</p>
<p>12.3 Reliability Requirements 248</p>
<p>12.4 Qualitative Reliability Analysis 256</p>
<p>12.5 Quantitative Reliability Budgeting and Modeling 259</p>
<p>12.6 Robustness Testing 260</p>
<p>12.7 Stability Testing 267</p>
<p>12.8 Field Performance Analysis 268</p>
<p>12.9 Reliability Roadmap 269</p>
<p>12.10 Hardware Reliability 270</p>
<p>13 DESIGN FOR RELIABILITY OF CLOUD SOLUTIONS 271</p>
<p>13.1 Solution Design for Reliability 271</p>
<p>13.2 Solution Scope and Expectations 273</p>
<p>13.3 Reliability Requirements 275</p>
<p>13.4 Solution Modeling and Analysis 279</p>
<p>13.5 Element Reliability Diligence 285</p>
<p>13.6 Solution Testing and Validation 285</p>
<p>13.7 Track and Analyze Field Performance 288</p>
<p>13.8 Other Solution Reliability Diligence Topics 292</p>
<p>14 SUMMARY 296</p>
<p>14.1 Service Reliability and Service Availability 297</p>
<p>14.2 Failure Accountability and Cloud Computing 299</p>
<p>14.3 Factoring Service Downtime 301</p>
<p>14.4 Service Availability Measurement Points 303</p>
<p>14.5 Cloud Capacity and Elasticity Considerations 306</p>
<p>14.6 Maximizing Service Availability 306</p>
<p>14.7 Reliability Diligence 309</p>
<p>14.8 Concluding Remarks 310</p>
<p>Abbreviations 311</p>
<p>References 314</p>
<p>About the Authors 318</p>
<p>Index 319</p>