Introduction to Front End pairing
The whole mechanism is based on the approach that Lync 2013 uses to manage the "presence" database (each Front End Server now controls the presence database) and on the Windows Fabric component, which is used to keep user data in sync on all the Front End servers. We will cover the Windows Fabric component later in this chapter.
When a pool hosting the Central Management Store (CMS) is paired with another pool, it creates a backup of the CMS and a Master/Standby relationship between the two database instances.
The aforementioned mechanism explains why, in Lync 2013, the dependency on the Back End Server has been "relaxed" (what happens is named lazy writes —the SQL Server database is updated mainly for the eventuality of a disaster recovery). To manage the new logic of the presence database, the algorithm used in Lync 2010 to determine where a user was homed (also if a failure occurred on one or more Front Ends) has been changed.
Now, we have Lync 2013 automatically...