Question about Semi-Synchronous Replication: the Answer with All the Details - Percona Community Blog
https://www.percona.com/community-blog/2018/08/23/question-about-semi-synchronous-replication-answer-with-all-the-details/

Semi-Synchronous Replication at Facebook
http://yoshinorimatsunobu.blogspot.com/2014/04/semi-synchronous-replication-at-facebook.html

Асинхронная репликация без цензуры / Олег Царёв (Mail.Ru Group)
https://www.youtube.com/watch?v=_r8vLPTl0PE