Disaster Recovery Options in Lync Server 2013

Lync Server 2013 has come a long way in providing disaster recovery options in a simplified manner. In Lync Server 2010, there were three options for disaster recovery:

• Backup Registrar—Backup registrar functionality was introduced in Lync Server 2010. This feature allowed pools to be configured as a backup for the registrar service only. In the event of a pool failure, users would register against the backup pool in limited functionality mode, essentially enabling users to make and receive calls. This was critical in providing the level of availability required for Enterprise Voice.

• Metropolitan Site Resiliency—This solution split pools between two physical servers. Geographically dispersed clusters were deployed to support SQL and file servers. Synchronous data replication was then deployed between the geographically dispersed clusters. This solution introduced unnecessary complexity to environments, requiring high-speed, high-latency WAN connectivity across physical sites using stretched VLANs. Although this solution worked for a unique set of enterprise customers, it did not provide an acceptable disaster recovery solution for the general population.

• Forced Failover—This solution resulted in deploying a secondary pool, and all supporting servers in the second physical site. The administrator would configure backups of all primary data and copy that data to the secondary site. In the event of a disaster, the data could be restored using DBIMPEXP.EXE, and users could be force-moved to the secondary site. This solution was the better of the two options, although it did result in a high RTO. Importing data and moving a large number of users could often take hours and had a heavy dependency on custom scripts and resource kit tools.

Lync Server 2013 combines the best of Forced Failover and Metropolitan Site Resiliency functionality in to an integrated disaster recovery model. Backup Registrar functionality remains in Lync Server 2013 and is unchanged. Lync Server 2013 introduces the concept of pool pairing, which allows for Lync Server 2013 to constantly replicate critical data across multiple server pools. Exactly how pool pairing works is described in a later section.

Lync Server 2013 pool pairing is the only supported disaster recovery method; previous methods are not supported, and are not recommended.

Table 15.5 outlines the disaster recovery capabilities in earlier versions of Lync as well as Lync Server 2013.

Table 15.5. Lync Server Disaster Recovery Capabilities