Summary

This article provides information about the support for various database-level SQL Server scaling, high-availability and failover features.

The information is intentionally simplified to provide a general overview of compatibility. For additional details about the technologies that are outlined, refer to documentation from Microsoft. 

Details

The table below describes various SQL Server technologies and their compatibility with the Sitecore platform [1].

	Support by Sitecore	Standby category	Automatic failover	Readable secondaries	Writable secondaries
Replication
Snapshot Replication	–	cold	–	–	–
Transactional Replication	Sitecore XP 9.0.0 and higher, Experimental for CMS 6.0– XP 8.2.7 [4]	warm	–	✓	–
Peer-to-Peer Replication	–	warm	–	–	–
Merge Replication	– [5]	warm	–	–	–
Azure Geo-Replication	Experimental [4]	warm	✓	✓	–
High-availability
Log Shipping	–	warm	–	–	–
Database Mirroring [2]	Sitecore CMS 6.6—8.1	warm, hot	✓	–	–
AlwaysOn Availability Groups [3]	Sitecore XP 8.2 and higher	warm, hot	✓	–	–

Notes

• [1] Various attributes of the SQL Server technologies mentioned are described as compatible with Sitecore. They do not describe full capabilities of the underlying technology. For example, Readable Secondaries are possible with AlwaysOn Availability Groups but they are not supported by Sitecore.
• [2] This feature will be removed from Microsoft SQL Server in the future. It is recommended to use AlwaysOn Availability Groups instead.
• [3] See the Sitecore XP 8.2 Release Notes and Configure SQL Server Always On articles for details.
• [4] There is experimental support for replicating Web databases. See the How to configure SQL Server Transactional Replication article for details.
  Sitecore officially supports using a read-only database for XP 9.0 and higher. To read more about experimental support for replication, click the following links:
  • Walkthrough: Replicating the Web database using Azure active geo-replication
  • Configure Content Delivery roles for separate EventQueue and Properties tables
• [5] Merge replication is not supported for the latest Sitecore versions, new implementations or version upgrades. Sitecore customers who use Merge replication in a production environment using Sitecore CMS versions 6.3—7.2 are supported in accordance with the Product Support Lifecycle and the Scope of Services.

Definitions

For the purpose of this article, the following definitions are used:

High-availability categories

Defines the risk of data loss and expected recovery time when using the corresponding technology.

	Cold Standby	Warm Standby	Hot Standby
Data Loss	Likely	Possible	No
Recovery Time	Hours	Minutes/Hours	Minutes

Automatic failover

Defines whether the setup allows Sitecore instances to automatically switch to failover/secondary SQL Database instance in case of an outage.

Readable secondaries

Defines whether the setup allows Sitecore instances to read data from secondary SQL databases, effectively enabling a content delivery scenario.

Writable secondaries

Defines whether the setup allows Sitecore instances to write data to secondary SQL databases, effectively enabling a content editing scenario.