Your company has a main office and a branch office. The main office is located in Amsterdam. The branch office is located in New York. Each office has a data center.
The offices connect to each other by using a high-bandwidth, low-latency wide area network (WAN) link.
You have a Skype for Business Server 2015 infrastructure that contains 5,000 users.
You plan to deploy a persistent chat infrastructure.
You need to ensure that persistent chat rooms remain available if a Persistent Chat Server fails.
What should you do?