When architecting a fault tolerant or high availability solution, one of the conditions that stymie designers is a split-brain configuration. This is where the data is different, not easily reconcilable, and none of the resources are the record of authority. The trick is the balance between both (fault tolerance and high availability) and the cost and resiliency with the underlying technology and its support. Modern security solutions have been elevated to Tier 1 status and must be operational all the time, with minimal to no downtime.”]
Source: https://www.csoonline.com/article/3269569/avoiding-split-brain-scenarios-for-security-solutions.html