| title | description | author | ms.author | ms.reviewer | ms.date | ms.service | ms.subservice | ms.topic | helpviewer_keywords | ||
|---|---|---|---|---|---|---|---|---|---|---|---|
Enable the availability group feature for a SQL Server instance |
Describes how to enable the Always On availability group feature for an instance of SQL Server. |
MashaMSFT |
mathoma |
maghan |
02/01/2024 |
sql |
availability-groups |
how-to |
|
[!INCLUDE SQL Server]
This article contains information about the requirements for configuring an instance of [!INCLUDE ssNoVersion] to support [!INCLUDE ssHADR] in [!INCLUDE ssnoversion].
Important
For essential information about [!INCLUDE ssHADR] prerequisites and restrictions for Windows Server Failover Clustering (WSFC) nodes and instances of [!INCLUDE ssNoVersion], see Prerequisites, Restrictions, and Recommendations for Always On Availability Groups (SQL Server).
Always On 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 hosted by a specific instance of [!INCLUDE ssNoVersion] and that maintains a local copy of each availability database that belongs to the availability group. Two 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 [!INCLUDE ssHADR] a server instance requires a unique, dedicated endpoint. All mirroring and availability group connections on a server instance use the same database mirroring endpoint. This special-purpose endpoint is used exclusively to receive these connections from other server instances.
To support [!INCLUDE ssHADR], a server instance must reside on a node in the WSFC failover cluster that hosts the availability group, be [!INCLUDE ssHADR] enabled and possessed a database mirroring endpoint.
-
Enable the Always On Availability Groups feature on every server instance to participate in one or more availability groups. A given server instance can host only a single availability replica for a given availability group.
-
Ensure that the server instance possesses a database mirroring endpoint.
To enable Always On Availability Groups
To determine whether a database mirroring endpoint exists
To create a database mirroring endpoint
-
Create a Database Mirroring Endpoint for Always On 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)
- Always On - HADRON Learning Series: Worker Pool Usage for HADRON Enabled Databases
- SQL Server Always On Team Blogs: The official SQL Server Always On Team Blog
- CSS SQL Server Engineers Blogs
- Microsoft SQL Server Always On Solutions Guide for High Availability and Disaster Recovery
- SQL Server Customer Advisory Team Whitepapers
- Overview of Always On Availability Groups (SQL Server)
- Prerequisites, Restrictions, and Recommendations for Always On Availability Groups (SQL Server)
- The Database Mirroring Endpoint (SQL Server)
- Always On Availability Groups: Interoperability (SQL Server)
- Failover Clustering and Always On Availability Groups (SQL Server)
- Windows Server Failover Clustering (WSFC) with SQL Server
- Always On Failover Cluster Instances (SQL Server)