---
title: Basic Availability Groups for a Single Database
description: Describes the differences between a regular and basic Always On availability group, and how to configure a basic availability group.
author: MashaMSFT
ms.author: mathoma
ms.reviewer: randolphwest
ms.date: 10/23/2025
ms.service: sql
ms.subservice: availability-groups
ms.topic: how-to
---
# Basic Always On availability groups for a single database

[!INCLUDE [SQL Server](../../../includes/applies-to-version/sqlserver.md)]

Always On basic availability groups provide a high availability solution for [!INCLUDE [sssql16-md](../../../includes/sssql16-md.md)] and later versions on Standard edition. A basic availability group supports a failover environment for a single database. It is created and managed much like traditional (advanced) [availability group](overview-of-always-on-availability-groups-sql-server.md) with Enterprise edition. The differences and limitations of basic availability groups are summarized in this document.

## Features

Basic availability groups replace the deprecated Database Mirroring feature, and provide a similar level of feature support. Basic availability groups enable a primary database to maintain a single replica. This replica can use either synchronous-commit mode or asynchronous-commit mode. For more information about availability modes, see [Differences between availability modes for an Always On availability group](availability-modes-always-on-availability-groups.md). The secondary replica remains inactive unless there's a need to fail over. This failover reverses the primary and secondary role assignments, causing the secondary replica to become the primary active database. For more information on failover, see [Failover and Failover Modes](failover-and-failover-modes-always-on-availability-groups.md). Basic availability groups can operate in a hybrid environment that spans on-premises and Microsoft Azure.

## Limitations

Basic availability groups use a subset of features compared to advanced availability groups on [!INCLUDE [sssql16-md](../../../includes/sssql16-md.md)] Enterprise edition. Basic availability groups include the following limitations:

- Limit of two replicas (primary and secondary). Basic Availability Groups for [!INCLUDE [sssql17-md](../../../includes/sssql17-md.md)] on Linux support an extra configuration only replica.

- No read access on secondary replica.

- No backups on secondary replica.

- No integrity checks on secondary replicas.

- No support for replicas hosted on servers running a version of SQL Server before [!INCLUDE [sssql16-md](../../../includes/sssql16-md.md)].

- Support for one availability database.

- Basic availability groups can't be upgraded to advanced availability groups. The group must be dropped and readded to a group that contains servers running only [!INCLUDE [sssql16-md](../../../includes/sssql16-md.md)] Enterprise edition.

- Basic availability groups are only supported for Standard edition servers.

- Basic availability groups can't be part of a distributed availability group.

- You might have multiple Basic availability groups connected to a single instance of SQL Server.

## Configuration

An Always On basic availability group can be created on any two [!INCLUDE [sssql16-md](../../../includes/sssql16-md.md)] Standard edition servers. When you create a basic availability group, you must specify both replicas during creation.

To create a basic availability group, use the `CREATE AVAILABILITY GROUP` Transact-SQL command and specify the `WITH BASIC` option (the default is `ADVANCED`). You can also create the basic availability group using the UI in SQL Server Management Studio starting with version 17.8. For more information, see [CREATE AVAILABILITY GROUP](../../../t-sql/statements/create-availability-group-transact-sql.md).

See the following example for creating a basic availability group using Transact-SQL (T-SQL):

```sql
CREATE AVAILABILITY GROUP [BasicAG]
WITH (AUTOMATED_BACKUP_PREFERENCE = PRIMARY,
BASIC,
DB_FAILOVER = OFF,
DTC_SUPPORT = NONE,
REQUIRED_SYNCHRONIZED_SECONDARIES_TO_COMMIT = 0)
FOR DATABASE [AdventureWorks]
REPLICA ON N'SQLVM1\MSSQLSERVER' WITH (ENDPOINT_URL = N'TCP://SQLVM1.Contoso.com:5022', FAILOVER_MODE = AUTOMATIC, AVAILABILITY_MODE = SYNCHRONOUS_COMMIT, SEEDING_MODE = AUTOMATIC, SECONDARY_ROLE(ALLOW_CONNECTIONS = NO)),
    N'SQLVM2\MSSQLSERVER' WITH (ENDPOINT_URL = N'TCP://SQLVM2.Contoso.com:5022', FAILOVER_MODE = AUTOMATIC, AVAILABILITY_MODE = SYNCHRONOUS_COMMIT, SEEDING_MODE = AUTOMATIC, SECONDARY_ROLE(ALLOW_CONNECTIONS = NO));

GO
```

> [!NOTE]  
> The limitations of basic availability groups apply to the `CREATE AVAILABILITY GROUP` command when `WITH BASIC` is specified. For example, you get an error if you attempt to create a basic availability group that permits read access. Other limitations apply in the same manner. Refer to the Limitations section of this article for details.

## Related content

- [What is an Always On availability group?](overview-of-always-on-availability-groups-sql-server.md)