Introduction xvii Part I: Understanding High Availability 1 Understanding High Availability 1 Overview of High Availability 1 Calculating Availability 6 Availability Example: A 24×7×365 Application 6 The Availability Continuum 8 Availability Variables 10 General Design Approach for Achieving High Availability 13 Development Methodology with High Availability Built In 14 Assessing Existing Applications 16 What Is a Service Level Agreement? 17 High Availability Business Scenarios 18 An Application Service Provider 18 Worldwide Sales and Marketing--Brand Promotion 19 Investment Portfolio Management 20 Call-Before-You Dig Call Center 20 Microsoft Technologies That Yield High Availability 21 Summary 22 2 Microsoft High Availability Options 23 Getting Started with High Availability 23 Creating a Fault-Tolerant Disk: RAID and Mirroring 26 Increasing System Availability with RAID 27 Mitigating Risk by Spreading Out Server Instances 33 Microsoft Options for Building an HA Solution 35 Windows Server Failover Clustering (WSFC) 36 SQL Clustering 37 AlwaysOn Availability Groups 39 Data Replication 40 Log Shipping 41 Database Snapshots 42 Microsoft Azure Options and Azure SQL Databases 43 Application Clustering 45 Summary 46 Part II: Choosing the Right High Availability Approaches 3 Choosing High Availability 47 A Four-Step Process for Moving Toward High Availability 47 Step 1: Launching a Phase 0 HA Assessment 49 Resources for a Phase 0 HA Assessment 49 The Phase 0 HA Assessment Tasks 49 Step 2: Gauging HA Primary Variables 52 Step 3: Determining the Optimal HA Solution 53 A Hybrid High Availability Selection Method 53 Step 4: Justifying the Cost of a Selected High Availability Solution 75 ROI Calculation 75 Adding HA Elements to Your Development Methodology 76 Summary 76 Part III: Implementing High Availability 4 Failover Clustering 79 Variations of Failover Clustering 80 How Clustering Works 81 Understanding WSFC 82 Extending WSFC with NLB 86 How WSFC Sets the Stage for SQL Server Clustering and AlwaysOn 87 Installing Failover Clustering 89 A SQL Clustering Configuration 94 An AlwaysOn Availability Group Configuration 95 Configuring SQL Server Database Disks 96 Summary 97 5 SQL Server Clustering 99 Installing SQL Server Clustering Within WSFC 100 Potential Problems to Watch Out for with SQL Server Failover Clustering 113 Multisite SQL Server Failover Clustering 114 Scenario 1: Application Service Provider with SQL Server Clustering 114 Summary 117 6 SQL Server AlwaysOn and Availability Groups 119 AlwaysOn and Availability Groups Use Cases 119 Windows Server Failover Clustering 120 AlwaysOn Failover Clustering Instances 120 AlwaysOn and Availability Groups 122 Combining Failover with Scale-out Options 125 Building a Multinode AlwaysOn Configuration 125 Verifying SQL Server Instances 126 Setting Up Failover Clustering 126 Preparing the Database 129 Enabling AlwaysOn HA 129 Backing Up the Database 130 Creating the Availability Group 131 Selecting the Databases for the Availability Group 132 Identifying the Primary and Secondary Replicas 133 Synchronizing the Data 135 Setting Up the Listener 138 Connecting Using the Listener 141 Failing Over to a Secondary 141 Dashboard and Monitoring 143 Scenario 3: Investment Portfolio Management with AlwaysOn and Availability Groups 145 Summary 148 7 SQL Server Database Snapshots 149 What Are Database Snapshots? 150 Copy-on-Write Technology 154 When to Use Database Snapshots 155 Reverting to a Snapshot for Recovery Purposes 155 Safeguarding a Database Prior to Making Mass Changes 157 Providing a Testing (or Quality Assurance) Starting Point (Baseline) 157 Providing a Point-in-Time Reporting Database 158 Providing a Highly Available and Offloaded Reporting Database from a Database Mirror 159 Setup and Breakdown of a Database Snapshot 160 Creating a Database Snapshot 161 Breaking Down a Database Snapshot 165 Reverting to a Database Snapshot for Recovery 166 Reverting a Source Database from a Database Snapshot 166 Using Database Snapshots with Testing and QA 167 Security for Database Snapshots 168 Snapshot Sparse File Size Management 168 Number of Database Snapshots per Source Database 168 Adding Database Mirroring for High Availability 168 What Is Database Mirroring? 169 When to Use Database Mirroring 171 Roles of the Database Mirroring Configuration 171 Playing Roles and Switching Roles 172 Database Mirroring Operating Modes 172 Setting Up and Configuring Database Mirroring 173 Getting Ready to Mirror a Database 174 Creating the Endpoints 176 Granting Permissions 178 Creating the Database on the Mirror Server 178 Identifying the Other Endpoints for Database Mirroring 180 Monitoring a Mirrored Database Environment 182 Removing Mirroring 185 Testing Failover from the Principal to the Mirror 187 Client Setup and Configuration for Database Mirroring 189 Setting Up DB Snapshots Against a Database Mirror 190 Reciprocal Principal/Mirror R.