Summary
Replication keeps live copies for availability and read scaling. Backups preserve point-in-time recovery for data loss, corruption, or accidental deletion.
Interview Points
- Replication is not a backup because bad writes can replicate too.
- Backups need retention, restore testing, and point-in-time recovery goals.
- Replication can be synchronous or asynchronous.
- Backups support disaster recovery and compliance.
- Always define RPO and RTO.
2-3 Minute Interview Script
“Replication and backup are often confused. Replication keeps another live copy of data, usually for high availability, failover, or read scaling. Backup stores recoverable historical copies.
Replication does not protect you from every data loss scenario. If a bug deletes rows or corrupts data, that bad write may replicate quickly. A backup gives you a point-in-time recovery path.
In system design, I would define RPO and RTO. RPO is how much data loss is acceptable. RTO is how long recovery can take. Those numbers drive backup frequency, retention, replication mode, and disaster recovery design.
My interview line: replication helps the system stay up; backups help the business recover.”
Follow-Ups
- Why test restores?
- When choose synchronous replication?