Conferencing Resiliency and Backup Service

Lync Server 2010 introduced resiliency for the voice platform through Survivable Branch Appliances/Servers and the concept of primary and backup registrars. This allowed users to retain basic voice services during an outage, but all contact list and conferencing capabilities were lost until an administrator intervened to forcefully move users and restore information. Lync Server 2013’s focus around conferencing resiliency automates this process for administrators by replicating conference data between each Front End pool member for both the primary and the backup registrar.

This resiliency is achieved through a new Lync Backup Service that replicates user and conferencing data between paired Front End pools on a continuous basis. The advantage to this can be seen when an organization has two locations, each with an active pool paired to the opposite location. During a server outage, full conferencing functionality can be provided through the opposite site. Failover between the two pools is not automated and must be initiated by an administrator through a set of Lync Management Shell commands. The combination of SQL Mirroring and the Lync Backup Service allows organizations to achieve a new degree of local and remote resiliency, as shown in Figure 2.2.

Figure 2.2. Local and remote resiliency.

One negative change from Lync Server 2010 is that Front End pools can be paired only with the same product version, meaning an Enterprise Edition pool is not recommended to be paired with a Standard Edition pool. Additionally, pool pairings are now a 1:1 ratio so multiple Front End pools can no longer be paired with a single disaster recovery site’s Front End pool. A unique disaster recovery pool must be deployed for each primary pool, which means an even number of Front End pools are required for pairing.

Additionally, the conferencing resiliency benefits only users homed directly to the Front End pool. Users hosted on a Survivable Branch Appliance or Server still use a single Front End pool for voice resiliency, but do not gain resiliency for their conferencing.