Configuration of a Server Instance for AlwaysOn Availability Groups (SQL Server)

AlwaysOn Availability Groups

A high-availability and disaster-recovery solution that provides an enterprise-level replacement for database mirroring. An availability group supports a failover environment for a discrete set of user databases, known as availability databases, that fail over together.

availability replica

An instantiation of an availability group that is hosted by a specific instance of SQL Server and that maintains a local copy of each availability database that belongs to the availability group. Two types of availability replicas exist: a single primary replica and one to four secondary replicas. The server instances that host the availability replicas for a given availability group must reside on different nodes of a single Windows Server Failover Clustering (WSFC) cluster.

database mirroring endpoint

An endpoint is a SQL Server object that enables SQL Server to communicate over the network. To participate in database mirroring and/or AlwaysOn Availability Groups a server instance requires a special, dedicated endpoint. All mirroring and availability group connections on a server instance use the same database mirroring endpoint. This endpoint is a special-purpose endpoint used exclusively to receive these connections from other server instances.

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To support AlwaysOn Availability Groups, a server instance must reside on a node in the WSFC failover cluster that hosts the availability group, be AlwaysOn Availability Groups enabled, and possess a database mirroring endpoint.

1. Enable the AlwaysOn Availability Groups feature on every server instance that is to participate in one or more availability groups. A given server instance can host only a single availability replica for a given availability group.

2. Ensure that the server instance possesses a database mirroring endpoint.

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To enable AlwaysOn Availability Groups

• Enable and Disable AlwaysOn Availability Groups (SQL Server)

To determine whether a database mirroring endpoint exists

• sys.database_mirroring_endpoints (Transact-SQL)

To create a database mirroring endpoint

• Create a Database Mirroring Endpoint for AlwaysOn Availability Groups (SQL Server PowerShell)

• Create a Database Mirroring Endpoint for Windows Authentication (Transact-SQL)

• Allow a Database Mirroring Endpoint to Use Certificates for Outbound Connections (Transact-SQL)

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• Blogs: 

  AlwaysON - HADRON Learning Series: Worker Pool Usage for HADRON Enabled Databases

  SQL Server AlwaysOn Team Blogs: The official SQL Server AlwaysOn Team Blog

  CSS SQL Server Engineers Blogs

• Videos: 

  Microsoft SQL Server Code-Named "Denali" AlwaysOn Series,Part 1: Introducing the Next Generation High Availability Solution

  Microsoft SQL Server Code-Named "Denali" AlwaysOn Series,Part 2: Building a Mission-Critical High Availability Solution Using AlwaysOn

• Whitepapers: 

  Microsoft SQL Server AlwaysOn Solutions Guide for High Availability and Disaster Recovery

  Microsoft White Papers for SQL Server 2012

  SQL Server Customer Advisory Team Whitepapers

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Concepts