Configuring Aurora Replica to Prevent Promotion on Primary Instance Failure

Correct Answer: A.

Aurora Replicas serves two purposes,

To scale read operations for the application.

To promote as a Primary Instance, in case of failure in the primary instance.

In case of multiple Aurora Replicas, priority value can be used to control the order in which a Replica can be promoted as a primary instance.

Valid Range is from 0 to 15, with 0 as the highest priority.

If no priority values are set, it is assigned a default value as 1

In the above scenario, to make sure a new Replica is not promoted as a Primary instance, a lesser priority (higher number) than the existing priority value of 4 should be assigned to the new replica.

Option B is incorrect as Configuring priority as tier-0 will make it first preference to be promoted as Primary instance post failure in Primary instance.

Option C is incorrect as when the priority value is the same for two or more Aurora Replica, Replica with larger size is promoted as a primary instance.

Option D is incorrect as when priority is set as default, it selects value as tier-1

This will make new replicas a higher priority to be promoted as primary instances.

For more information on setting priority values for replicas in Amazon Aurora, refer to the following URLs,

https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/aurora-replicas-adding.html https://aws.amazon.com/blogs/aws/additional-failover-control-for-amazon-aurora/

To ensure that the newly added Aurora Replica does not get promoted as the primary instance in case of a failure of the primary instance, we need to configure its priority setting appropriately. The priority setting determines the order in which Aurora selects the Aurora Replicas to promote to the primary instance if the primary instance fails.

By default, Aurora replicas are assigned a priority setting of tier-0. This means that they have the highest priority and will be promoted to the primary instance in the event of a failure of the primary instance.

To prevent the new Aurora Replica from being promoted as the primary instance, we need to lower its priority setting to a value lower than the other Aurora Replicas in the cluster.

Option A suggests configuring the priority as tier-15 for the new Aurora Replica. This would make the new Aurora Replica have a higher priority than the existing Aurora Replicas, which defeats the purpose of the requirement. Therefore, option A is incorrect.

Option B suggests configuring the priority as tier-0 for the new Aurora Replica. As mentioned earlier, this is the default priority assigned to Aurora replicas and would result in the new Aurora Replica being promoted as the primary instance in case of a failure of the primary instance. Therefore, option B is also incorrect.

Option C suggests configuring the priority of the new Aurora Replica to be the same as another Aurora Replica in the cluster. This would work if the priority of the existing Aurora Replica is lower than the default priority of tier-0. However, if the priority of the existing Aurora Replica is tier-0, then this option would not work. Therefore, option C is partially correct.

Option D suggests configuring the priority of the new Aurora Replica to the default value. As we discussed earlier, this default value is tier-0, which would promote the new Aurora Replica as the primary instance in case of a failure of the primary instance. Therefore, option D is also incorrect.

In summary, the correct answer to the question is option C, which suggests configuring the priority of the new Aurora Replica to be the same as another Aurora Replica in the cluster with a lower priority than tier-0.