# Overview The leader uses the same [[Write-ahead Log (WAL)]] used on the data storage engine to communicate changes to the followers. # Key Considerations # Pros # Cons - The main disadvantage is that the log describes the data on a very low level: a WAL contains details of which bytes were changed in which disk blocks. This makes replication closely coupled to the storage engine. In other words, you can't replicate from something like mySQL to postgreSQL. # Use Cases # Related Topics