Back End database is a key for any two-tier or three-tier application. It might be deployed independently in the form of database server or as native database managed by application itself. Microsoft SQL server is play an important role with Microsoft UC platform either LCS/OCS or Lync/SfB. Since Lync Server 2013 onwards SQL server is loosely coupled with Back End Servers and most of the activities is used to happen on SQL express edition itself which is part of the Front End Servers. Still, Microsoft Lync Back End Server maintains copy of user persistent data, application data and Central Management Store.

Lync Server 2013 supports SQL Mirror and SQL Failover Clustering (Lync Server 2013 CU1 onwards) for Back End databases. While SQL Server AlwaysOn is not supported with Lync Server 2013.

SQL Server AlwaysOn was first introduced with SQL Server 2012. Now, Skype for Business Server supports all the options.

• SQL Mirror
• SQL Failover Clustering
• SQL AlwaysOn Availability groups
• SQL AlwaysOn Failover Cluster Instances (FCI)

One concern which always arise “Simple & Cost Effective Solution without performance compromise?” for better ROI with lower TCO. All four options use same SQL Server but edition and storage requirement make difference.

Database Mirroring is a simplest method for Skype for Business Back End Server which can be easily setup by Lync Server Topology Builder. To achieve automatically failover, deploy witness server. To use Failover Clustering, AlwaysOn Availability groups and AlwaysOn Failover Cluster Instances, you first setup and configure the Back End servers high availability solution.