Which Scenarios Can Data be Recovered with Read Replica? (Choose 2)
Question
You migrated an on-premise MySQL database to AWS RDS MySQL in region ap-southeast-1
The database has stored key information such as customers' phone numbers, addresses and date of birth.
In order to decrease the read load on the master DB instance, a Read Replica has been created in region ap-southeast-2
This Read Replica can also be promoted as a data recovery scheme if the source DB instance fails.
In which scenarios can the data be successfully recovered by the Read Replica? (Select TWO.)
Answers
Explanations
Click on the arrows to vote for the correct answer
A. B. C. D. E.Correct Answer - B, D.
When creating a Read Replica, the user can select another region so that updates made to the source DB instance are copied to the Read Replica in this new region:
When needed, this Read Replica can be promoted to be a new standalone instance.
Option A is incorrect: Because the data gets deleted in the Read Replica as well.
In this case, to recover the data, regular DB snapshots are needed.
Option B is CORRECT: Because the hardware failure only affects the master node.
Promoting the Read Replica can recover the database.
Option C is incorrect: Because it affects all regions and replicas may also be deleted.
Option D is CORRECT: Because Read Replica still exists and can be used to be a functional database.
Option E is incorrect: Because the hardware failure exists in both regions so that Read Replica may not fully work.
The scenario described in the question involves an on-premise MySQL database being migrated to AWS RDS MySQL in region ap-southeast-1, with a Read Replica created in region ap-southeast-2 to decrease read load on the master DB instance. The Read Replica can also be promoted as a data recovery scheme if the source DB instance fails.
The question asks which scenarios can the data be successfully recovered by the Read Replica, and the correct answers are A (Data has been deleted mistakenly by a bug in the application code) and B (A RDS hardware failure on the master instance).
Explanation:
A Read Replica is a copy of the source DB instance, and it can be used to offload read traffic from the master instance. Read Replicas can also be promoted to become standalone DB instances, which can be used for disaster recovery purposes in case the master instance fails.
In the scenario described in the question, a Read Replica has been created in a different region to the master DB instance. This provides an additional level of redundancy, as the Read Replica can be used to recover data in case of a regional failure.
Now, let's consider each of the scenarios given in the question:
A. Data has been deleted mistakenly by a bug in the application code. In this scenario, the data is still available on the Read Replica, as the deletion would have only affected the master DB instance. The Read Replica can be promoted to become a standalone DB instance, and the data can be recovered from there.
B. A RDS hardware failure on the master instance. In this scenario, the master instance has failed, and the data is no longer available on it. However, the Read Replica is still available and can be promoted to become a standalone DB instance. This will allow the data to be recovered.
C. AWS account is compromised. If the AWS account is compromised, it is possible that the attacker may have access to the master DB instance and the Read Replica. In this case, it is not recommended to use the Read Replica for data recovery, as the attacker may have also compromised the Read Replica. Instead, other recovery options such as backups should be considered.
D. The master database instance has been mistakenly deleted. If the master DB instance has been mistakenly deleted, the data is no longer available on it. However, if a recent backup of the master instance is available, it can be used to restore the data to a new master instance. The Read Replica, on the other hand, cannot be used for data recovery in this scenario, as it is still a copy of the deleted master instance.
E. An AWS regional failure happening in both ap-southeast-1 and ap-southeast-2. If a regional failure occurs in both ap-southeast-1 and ap-southeast-2, both the master DB instance and the Read Replica will be affected. In this case, other recovery options such as backups or multi-region replication should be considered.
In conclusion, the Read Replica can be used for data recovery in case of scenarios A and B, but it may not be the best option in all situations. It is important to have a well-designed disaster recovery plan that takes into account all possible scenarios and includes multiple recovery options.