What is the maximum number of MySQL servers in a group?
A group can consist of maximum 9 servers. Attempting to add another server to a group with 9 members causes the request to join to be refused. This limit has been identified from testing and benchmarking as a safe boundary where the group performs reliably on a stable local area network.

一个组中包括最多9台服务器。尝试添加一个服务器到这个有9台服务器的组中会导致请求被拒绝。这个限制在测试和基准测试中被证明，作为一个安全边界。在这个边界内，在一个稳定的本地网络上，组复制可以可靠的运行。