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Answer: MTTD: 5 MTTR: 20 MTBF: 90 Impact: 33%
The question provides a scenario where the new database system takes twice as long to successfully fail over between zones compared to the current system. The current system has a Mean Time to Repair (MTTR) of 10 minutes for a database failure. Therefore, with the new system, the MTTR would double to 20 minutes. The Mean Time to Detect (MTTD) remains the same at 5 minutes, as the detection time is not affected by the failover time. The Mean Time Between Failure (MTBF) is given as once per quarter, which translates to 90 days, and this remains unchanged as it is based on the frequency of failures, not the failover time. The User Impact Percentage is stated to be divided between three zones, so affecting one zone would impact approximately 33% of the users. This percentage does not change with the new system's failover time. Therefore, the correct values for the risk of database failover with the new system are MTTD: 5, MTTR: 20, MTBF: 90, Impact: 33%.
Author: LeetQuiz Editorial Team
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Your product is deployed across three Google Cloud Platform (GCP) zones, with users distributed among them. Failover between zones is possible but results in a 10-minute service disruption for affected users. Database failures occur once per quarter and are detected within five minutes. You are evaluating reliability risks for a new real-time chat feature, cataloging the following for each risk:
The chat feature introduces a new database system with a failover time twice as long as the current system. You need to determine the risk values for the new database failing in one zone. What are the MTTD, MTTR, MTBF, and User Impact Percentage for this scenario?
A
MTTD: 5 MTTR: 10 MTBF: 90 Impact: 33%
B
MTTD: 5 MTTR: 20 MTBF: 90 Impact: 33%
C
MTTD: 5 MTTR: 10 MTBF: 90 Impact: 50%
D
MTTD: 5 MTTR: 20 MTBF: 90 Impact: 50%
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