High availability design: Are mirrored or replicated databases commonly included in high-availability (HA) systems to reduce downtime risk?

Introduction / Context:
High availability aims to minimize service interruption. Database mirroring and replication provide redundancy so that if a primary fails, a secondary can take over quickly with minimal data loss.

Given Data / Assumptions:

• HA targets include recovery time objective (RTO) and recovery point objective (RPO).
• Techniques include synchronous replication, asynchronous replication, log shipping, clustering, and managed cloud replicas.
• Failover may be automatic or manual.

Concept / Approach:
Mirroring/replication maintains one or more up-to-date copies of data. In synchronous modes, commits are confirmed only after the mirror acknowledges, achieving near-zero RPO. In asynchronous modes, performance improves at the cost of small potential data lag. Both patterns are widely used in HA architectures across on-premises and cloud environments.

Step-by-Step Solution:
Define RTO/RPO targets with stakeholders.Choose replication technology (native DB features, cluster, or cloud-managed).Configure monitoring, health checks, and failover procedures.Regularly test failover and validate data integrity on secondaries.

Verification / Alternative check:
Perform a controlled failover drill. If applications recover within target RTO and data loss is within RPO, the HA design is effective.

Why Other Options Are Wrong:
Limiting replicas to reporting ignores HA use cases. HA applies equally in cloud and on-prem. Marking “Incorrect” would deny a standard industry practice.

Common Pitfalls:
Unvalidated failover runbooks; untested backups; split-brain risk without quorum; assuming synchronous replication needs no latency planning.

Final Answer:
Correct