Understanding the Impact of Pilot Light DR Strategy in Network - RTO / RPO

Correct Answer: D.

RTO is the maximum acceptable delay between the interruption once disaster strikes and restoration of service.

RPO is the maximum acceptable amount of time since the last data recovery point at which all data is replicated to the DR location.

With Pilot Light DR Strategy, data replication between production & backup databases is always active.

Application servers in the DR location are configured but are in shut mode.

With this strategy, when there is a disaster, loss in data will be in minutes while it will take hours to initiate application servers in the DR location.

Options A, B & C are incorrect as with Pilot Light DR strategy, RPO will be in minutes & RTO will be in hours.

Following will be RTO/RPO values for each DR strategy,

Backup and restore: RPO will be in hours, while RTO will be less than 24 hours.

Pilot light: RPO will be in minutes while RTO will be in hours.

Warm standby: RPO will be in seconds, while RTO will be in minutes.

Multi-region (multi-site) active-active: RPO will be zero while RTO will be potentially zero.

For more information on RTO/RPO with different DR strategies, refer to the following URL,

https://docs.aws.amazon.com/wellarchitected/latest/reliability-pillar/plan-for-disaster-recovery-dr.html

In the context of Disaster Recovery (DR), RPO (Recovery Point Objective) and RTO (Recovery Time Objective) are two important metrics that help to determine the effectiveness of the DR strategy.

RPO refers to the maximum amount of data loss that an organization can tolerate after a disruption occurs. It is the point in time to which the data must be restored after a disruption in order to resume normal operations.

RTO refers to the maximum allowable downtime for an application or system after a disruption occurs. It is the duration of time within which the system or application must be restored to its normal operating state.

In the given scenario, the design team has implemented a Pilot Light DR strategy between production servers deployed at AWS us-east-1 region and backup servers deployed at on-premises data centers.

A Pilot Light DR strategy is a type of DR strategy that involves running a minimal version of the application in the DR site. In this scenario, the backup servers at the on-premises data center are only storing the data needed to bring the production environment back online.

Now, let's analyze the given answer options:

A. RPO will be in hours, while RTO will be less than 24 hours. This statement implies that the RPO will be in the order of hours and the RTO will be less than 24 hours. This may be true for some applications, but it cannot be generalized for all. Without knowing the specifics of the application, it is difficult to determine the accuracy of this statement.

B. RPO will be zero while RTO will be potentially zero. This statement implies that there will be no data loss and no downtime in the event of a disruption. This is unlikely to be the case for any system, as there is always some amount of data loss and downtime in a DR scenario.

C. RPO will be in seconds, while RTO will be in minutes. This statement implies that the RPO will be very low, in the order of seconds, and the RTO will be a few minutes. This is a reasonable statement for a Pilot Light DR strategy, as it involves replicating only the essential components of the production environment to the DR site, resulting in a quick recovery time.

D. RPO will be in minutes while RTO will be in hours. This statement implies that the RPO will be in the order of minutes, and the RTO will be in the order of hours. This may be true for some applications, but it cannot be generalized for all. Without knowing the specifics of the application, it is difficult to determine the accuracy of this statement.

Therefore, option C is the correct statement to justify the impact of implementing a Pilot Light DR strategy in terms of RTO/RPO, as it is a reasonable statement for a Pilot Light DR strategy.