Tag Archives: Skype for Business BackEnd server

Skype for Business Server 2015 Databases

Skype for Business Server 2015 databases are as same as it was in Lync Server 2013. Skype for Business Server 2015 installs SQL Server 2014 Express Edition (64-bit) for local configuration databases while SQL Server 2014/SQL Server 2012 SP2 with CU2/SQL Server 2008 R2 SP2 can be deployed for Back End databases, Archiving, Monitoring, Persistent Chat and Persistent Chat Compliance databases. Below are the graphical representation of databases placement in Standard and Enterprise Edition.

Explanation of each databases:

xds: xds is the main database of SfB Server and part of central management store which maintain the topology information, polices, configuration etc. and replicate a read only copy to each SfB server.

rtcxds: rtcxds maintains the backup for user data

rtcshared: rtcshared hosts the conferencing directory

rtcab: rtcab stands for real time communication address book and maintain the address book service information

cpsdyn: cpsdyn maintains the dynamic information database for Call Park application.

rgsconfig: rgsconfig maintains the response group configuration service data file.

rgsdyn: rgsconfig maintains the runtime data for response group configuration service data file.

xds: xds on SfB frontend server maintain a read only copy of xds database which is part of central management store and resides in SQL backend database server.

rtc: rtc store persistent users data such as contact list, schedule conferences and ACL’s etc.

rtcdyn: rtcdyn maintains dynamic user data such as presence.

lyss: lyss stands for Lync Storage Service and used to maintain HA within a FE pool. It is a blob database and abstract writes to backend database. It maintains a copy of the data within Front End servers in the pool temporarily, and delete that data once it has been delivered to the final database server. It is a replacement for MSMQ which was used in previous version of Lync. Therefore, it is part of the Front End servers and it is located under LYNCLOCAL named instance. It is also used for Archiving integration and Unified Contact Center. Currently, it supports Exchange and SQL for archiving.

lcslog: lcslog maintains data file for the retention of instant messaging and conferencing data on an Archiving Server.

cdr: cdr stands for call detail recording and maintains the call detail recording data.

QoE: QoE stands for quality of Experience and maintains the QoE data to provide best experience to SfB users.

mgc: maintains user persistent chat data.

mgccomp: maintains compliance data persistent chat.


Back End Server options: Skype for Business 2015

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.