Explain the concept of replication in data storage systems or databases.

Replication in storage systems and databases is the process of copying and maintaining up-to-date copies of data on multiple servers or nodes.

Goals of replication:

• Increased fault tolerance: if one node fails, data is available on another.
• Improved read performance: requests can be distributed among replicas.
• Geographical distribution of data to reduce latency.

Types of replication:

• Master-Slave (Primary-Replica): writes are made to the master, and changes are asynchronously or synchronously copied to slaves.
• Multi-master: multiple nodes can accept writes, requiring conflict resolution.

Example in a database:

// Pseudocode for writing to master and reading from replica
func WriteData(data string) {
    masterDB.Insert(data)
}

func ReadData(id int) string {
    return replicaDB.Query(id)
}

Replication requires synchronization setup and data consistency management.