This section describes master slave and DR configurations.

Master-slave configuration: Replication requires multiple copies of data to be dispersed across different databases. In such a setup, the read-only operations will be faster and scalable as it is possible to read from the nearest database instance and it can answer a number of read-only queries in parallel.

DR configuration: This involves copying the data from the primary instance to all its backup and standby instances so that it is easy to switch in case of failover. Replication is a practice followed by storage systems, database servers, and in cases of application configurations.

The two main types of replication configuration are:

• Active replication: In this configuration, the request from the client is processed by all instances. This configuration is used for real-time systems.
• Passive replication: In this configuration, the primary node processes the request, and it is then copied over to secondary nodes.

This pattern is usually implemented in software, often as part of the database management system. Additional hardware is introduced to give tolerance to both hardware and software failure and maintenance.