Deploy high availability and disaster recovery
Skype for Business Server offers high availability with server pooling, disaster recovery with pool pairing, and several modes of Back End Server high availability, including AlwaysOn Availability groups, database mirroring, and SQL failover clustering.
High availability refers to making sure that Skype for Business Server services are available even if one or more servers goes down.Disaster recovery refers to keeping services going in the event of a natural or human-caused disaster, and preserving as much data from before the disaster as possible.
This section tells how to deploy these features, and also covers what steps you can take for high availability and disaster recovery for some of your other server roles.
SQL Mirroring is available in Skype for Business Server 2015 but is no longer supported in Skype for Business Server 2019. The AlwaysOn Availability Groups, AlwaysOn Failover Cluster Instances (FCI), and SQL failover clustering methods are preferred with Skype for Business Server 2019.