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high-availability-solutions-sql-server.md

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title High Availability Solutions (SQL Server) | Microsoft Docs
ms.custom
ms.date 05/19/2016
ms.prod sql
ms.prod_service high-availability
ms.reviewer
ms.suite sql
ms.technology high-availability
ms.tgt_pltfrm
ms.topic conceptual
helpviewer_keywords
high availability [SQL Server], solutions
Database Engine [SQL Server], availability
database availability [SQL Server]
availability [SQL Server]
server availability [SQL Server]
ms.assetid b2eda634-0f8e-4703-801b-7ba895544ff5
caps.latest.revision 84
author MikeRayMSFT
ms.author mikeray
manager craigg

High Availability Solutions (SQL Server)

[!INCLUDEappliesto-ss-xxxx-xxxx-xxx-md] This topic introduces several [!INCLUDEssNoVersion] high-availability solutions that improve the availability of servers or databases. A high-availability solution masks the effects of a hardware or software failure and maintains the availability of applications so that the perceived downtime for users is minimized.

Note! Want to know which [!INCLUDEssNoVersion] editions support a given high availability solution? See the "High Availability (Always On)" section of Features Supported by the Editions of SQL Server 2016.

Overview of SQL Server High-Availability Solutions

[!INCLUDEssNoVersion] provides several options for creating high availability for a server or database. The high-availability options include the following:

  • Always On Failover Cluster Instances
    As part of the [!INCLUDEssNoVersion] Always On offering, Always On Failover Cluster Instances leverages Windows Server Failover Clustering (WSFC) functionality to provide local high availability through redundancy at the server-instance level—a failover cluster instance (FCI). An FCI is a single instance of [!INCLUDEssNoVersion] that is installed across Windows Server Failover Clustering (WSFC) nodes and, possibly, across multiple subnets. On the network, an FCI appears to be an instance of [!INCLUDEssNoVersion] running on a single computer, but the FCI provides failover from one WSFC node to another if the current node becomes unavailable.

For more information, see Always On Failover Cluster Instances (SQL Server).

  • [!INCLUDEssHADR]
    [!INCLUDEssHADR] is an enterprise-level high-availability and disaster recovery solution introduced in [!INCLUDEssSQL11] to enable you to maximize availability for one or more user databases. [!INCLUDEssHADR] requires that the [!INCLUDEssNoVersion] instances reside on Windows Server Failover Clustering (WSFC) nodes. For more information, see Always On Availability Groups (SQL Server).

Note! An FCI can leverage [!INCLUDEssHADR] to provide remote disaster recovery at the database level. For more information, see Failover Clustering and Always On Availability Groups (SQL Server).

  • Database mirroring. Note! [!INCLUDEssNoteDepFutureAvoid] We recommend that you use [!INCLUDEssHADR] instead.
    Database mirroring is a solution to increase database availability by supporting almost instantaneous failover. Database mirroring can be used to maintain a single standby database, or mirror database, for a corresponding production database that is referred to as the principal database. For more information, see Database Mirroring (SQL Server).

  • Log shipping
    Like [!INCLUDEssHADR] and database mirroring, log shipping operates at the database level. You can use log shipping to maintain one or more warm standby databases (referred to as secondary databases) for a single production database that is referred to as the primary database. For more information about log shipping, see About Log Shipping (SQL Server).

Recommended Solutions for Using SQL Server to Protect Data

Our recommendation for providing data protection for your [!INCLUDEssNoVersion] environment:

  • For data protection through a third-party shared disk solution (a SAN), we recommend that you use Always On Failover Cluster Instances.

  • For data protection through [!INCLUDEssNoVersion], we recommend that you use [!INCLUDEssHADR].

    We recommend using log shipping if you are running an edition of [!INCLUDEssNoVersion] that does not support [!INCLUDEssHADR]. For information about which editions of [!INCLUDEssNoVersion] support [!INCLUDEssHADR], see the "High Availability (Always On)" section of Features Supported by the Editions of SQL Server 2016.

See Also

Windows Server Failover Clustering (WSFC) with SQL Server
Database Mirroring: Interoperability and Coexistence (SQL Server)
Deprecated Database Engine Features in SQL Server 2016