[btgeekboy]

> If you need HA on a database, use the built-in replication service available on just about every database product in existence.

There are often valid reasons to not do this. For example, MySQL does not guarantee consistency between a source and its destination. mysqlrplsync can do this as a bandage, but it's something extra you need to set up and configure.

[cpuguy83]

I do not think this is a reason to not use replication. In this sense, no distributed system guarantees consistency. If a node goes down (particularly a leader!) while trying to distribute a new update, you are very likely to run into issues.

Replication != backup