--- title: "High Availability Solutions (SQL Server) | Microsoft Docs" ms.custom: "" ms.date: "06/13/2017" ms.prod: "sql-server-2014" ms.reviewer: "" ms.technology: high-availability 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 author: MikeRayMSFT ms.author: mikeray manager: craigg --- # High Availability Solutions (SQL Server) This topic introduces several [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] 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] > For information about which editions of [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] support a given high availability solution, see the "High Availability (AlwaysOn)" section of [Features Supported by the Editions of SQL Server 2014](../../getting-started/features-supported-by-the-editions-of-sql-server-2014.md). (#RecommendedSolutions) ## Overview of SQL Server High-Availability Solutions [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] provides several options for creating high availability for a server or database. The high-availability options include the following: AlwaysOn Failover Cluster Instances As part of the [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] AlwaysOn offering, AlwaysOn 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 [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] 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 [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] 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 [AlwaysOn Failover Cluster Instances (SQL Server)](windows/always-on-failover-cluster-instances-sql-server.md). [!INCLUDE[ssHADR](../../includes/sshadr-md.md)] [!INCLUDE[ssHADR](../../includes/sshadr-md.md)] is an enterprise-level high-availability and disaster recovery solution introduced in [!INCLUDE[ssSQL11](../../includes/sssql11-md.md)] to enable you to maximize availability for one or more user databases. [!INCLUDE[ssHADR](../../includes/sshadr-md.md)] requires that the [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] instances reside on Windows Server Failover Clustering (WSFC) nodes. For more information, see [AlwaysOn Availability Groups (SQL Server)](../../database-engine/availability-groups/windows/always-on-availability-groups-sql-server.md). > [!NOTE] > An FCI can leverage [!INCLUDE[ssHADR](../../includes/sshadr-md.md)] to provide remote disaster recovery at the database level. For more information, see [Failover Clustering and AlwaysOn Availability Groups (SQL Server)](../../database-engine/availability-groups/windows/failover-clustering-and-always-on-availability-groups-sql-server.md). Database mirroring > [!NOTE] > [!INCLUDE[ssNoteDepFutureAvoid](../../includes/ssnotedepfutureavoid-md.md)] We recommend that you use [!INCLUDE[ssHADR](../../includes/sshadr-md.md)] 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)](../../database-engine/database-mirroring/database-mirroring-sql-server.md). Log shipping Like [!INCLUDE[ssHADR](../../includes/sshadr-md.md)] 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)](../../database-engine/log-shipping/about-log-shipping-sql-server.md). ## Recommended Solutions for Using SQL Server to Protect Data Our recommendation for providing data protection for your [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] environment are as follows: - For data protection through a third-party shared disk solution (a SAN), we recommend that you use AlwaysOn Failover Cluster Instances. - For data protection through [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)], we recommend that you use [!INCLUDE[ssHADR](../../includes/sshadr-md.md)]. > [!NOTE] > If you are running an edition of [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] that does not support [!INCLUDE[ssHADR](../../includes/sshadr-md.md)], we recommend log shipping. For information about which editions of [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] support [!INCLUDE[ssHADR](../../includes/sshadr-md.md)], see the "High Availability (AlwaysOn)" section of [Features Supported by the Editions of SQL Server 2014](../../getting-started/features-supported-by-the-editions-of-sql-server-2014.md). ## See Also [Windows Server Failover Clustering (WSFC) with SQL Server](windows/windows-server-failover-clustering-wsfc-with-sql-server.md) [Database Mirroring: Interoperability and Coexistence (SQL Server)](../../database-engine/database-mirroring/database-mirroring-interoperability-and-coexistence-sql-server.md) [Deprecated Database Engine Features in SQL Server 2014](../../database-engine/deprecated-database-engine-features-in-sql-server-2016.md)