High availability. What does crossover mean in this context?

Question

I am working on a Mesos environment to do some tasks, and this seems like a great opportunity to learn about creating a highly accessible system. To this end, I am engaged in reading distributed systems, and I made a mistake when visiting wikipedia .

This section deals with the principle of HA development:

Reliable crossover . In multi-threaded systems, the crossover point itself tends to become a single point of failure. High availability technical support should provide a reliable crossover.

My google-fu teaches me three things:

1) audio intersection devices share one input into several outputs

2) genetic algorithms use crossover to combine solutions

3) buzzwordy white documents all copied from this wikipedia article: /

My question is: What does “intersection point” mean in this context and why is it the only point of failure?

Answer 1

A reliable crossover in this context means:

Ability to switch from node X (which is somehow broken) to node Y without data loss.

Invalid HA database example:
Copy the database every 5 minutes to a passive node. => here you can lose up to 5 minutes of data. => here the copy action is the only point of failure

Reliable HA database example:
Setting up data replication, where (for example) the insert statement is returned only as "done OK" when the transaction is copied to the secondary server. (yes: data replication is more complicated, then this, this is a simplified example in the context of the question)