What are the advantages of replication? What are its costs?

Replication is the process of copying data from one server (master) to others (replicas) to increase availability and fault tolerance.

Advantages:

• Increased fault tolerance: in case of a failure of the main server, replicas can continue to serve requests.
• Load balancing: read operations can be distributed among replicas, relieving the main server.
• Fast data recovery in case of failures.

Disadvantages:

• Increased write latency, as data needs to be synchronized across replicas.
• Possible data inconsistency (especially with asynchronous replication).
• Additional resources for storing and maintaining replicas.
• Complexity in managing and monitoring replication.

An example in Go might involve working with a database where reads are directed to replicas, and writes are directed to the master, but the replication mechanism itself is usually implemented at the database level.