There is something called failover technology in Amazon. AWS RDS's Multi-AZ deployment uses this technology. If you enable Multi-AZ for an RDS DB, say MySQL DB, RDS automatically creates a standby replica in a different AZ. If the primary DB instance is in AZ-1A, then RDS creates a standby replica in AZ-1B (for example). Suppose I add a new row to a table in the primary DB, then the same row is added, almost in the same time, in the standby replica. This is called as synchronous replication . Thus, standby replicas are useful during DB instance failure/ AZ disruption . How? Because, there is no need to create a backup later because the backup has already been created. This gives high availability during planned system maintenance. Normal backup operation - I/O activities are blocked in the primary database Automated backup operation (standby replica) - I/O activities are not blocked This standby replica is not similar to read replica (which is used for disaster recovery). S...
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