A data engineer is implementing a disaster recovery solution for a critical database. The business has a Recovery Point Objective (RPO) of 4 hours and a Recovery Time Objective (RTO) of 8 hours. Which solution would be most cost-effective while meeting these requirements?
- ADaily full backups shipped off-site, with manual restoration upon disaster
- BSynchronous replication to a hot standby in a remote data center
- CHourly transaction log backups combined with daily full backups, restored to a cold standby
- DAsynchronous replication to a warm standby in a remote data center
Show answer & explanationAnswer & explanation
Correct answer: C. Hourly transaction log backups combined with daily full backups, restored to a cold standby
An RPO of 4 hours means data loss up to 4 hours is acceptable, making hourly transaction log backups sufficient. An RTO of 8 hours allows for the time-consuming process of restoring a full backup and applying log backups to a cold standby, which is generally the most cost-effective approach for these RPO/RTO targets compared to more complex and expensive replication or hot/warm standby solutions.
Why the other options are wrong
- A. Daily full backups would result in an RPO of up to 24 hours (if the disaster occurs just before the next backup), which violates the 4-hour RPO requirement.
- B. Synchronous replication and a hot standby are designed for RPO near zero and very low RTO, which is overkill and significantly more expensive than needed for an RPO of 4 hours and RTO of 8 hours.
- D. Asynchronous replication to a warm standby could meet the RPO/RTO, but hourly log backups to a cold standby is likely more cost-effective for these specific targets.
Cold Standby
A cold standby system is a duplicate system that is powered off and not actively running. In a disaster, it must be powered on, configured, and data restored to it, leading to a longer Recovery Time Objective (RTO) but lower operational cost.
- System is powered off or minimally configured.
- Requires manual intervention to bring online.
- Lowest cost among standby options, but highest RTO.
Memory trick: RPO/RTO: The budget dance, cold is cheap, hot's a chance.