Persistent Chat High-Availability

Lync Server Persistent Chat contains two key components, a backend and a front end. The backend component is SQL based, and follows the same rules for redundancy as described in the “SQL Server Backend High-Availability” section. When deploying Persistent Chat, you can use the same SQL Servers used for your Front End pools, or deploy new SQL Servers for Persistent Chat.

Persistent Chat Front End Servers act much like Lync Front End Servers. These servers can be configured in a pool, with up to eight servers in each pool. However, only four servers may ever be active in a pool at a time. DNS load balancing is used to distribute traffic among the four active servers. Hardware load balancing is not supported for distributing traffic to Persistent Chat servers.

Stretched Persistent Chat pools are covered in the “Persistent Chat Disaster Recovery” section later in this chapter.