Your product is currently deployed in three Google Cloud Platform (GCP) zones with your users divided between the zones. You can fail over from one zone to another, but it causes a 10-minute service disruption for the affected users. You typically experience a database failure once per quarter and can detect it within five minutes. You are cataloging the reliability risks of a new real-time chat feature for your product. You catalog the following information for each risk:
* Mean Time to Detect (MTTD) in minutes
* Mean Time to Repair (MTTR) in minutes
* Mean Time Between Failure (MTBF) in days
* User Impact Percentage
The chat feature requires a new database system that takes twice as long to successfully fail over between zones. You want to account for the risk of the new database failing in one zone. What would be the value for the risk of database failover with the new system?
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%
Disclaimer
This is a practice question. There is no guarantee of coming this question in the certification exam.
Answer
B
Explanation
Maths: Answer B
MTTD stays 5 as no change in it
MTTR doubles to 20 minutes because question says “a new database system that takes twice as long to successfully fail over between zones.”
MTBF stays the same i.e., once per quarter (90 days).
Impact: 33% because if one zone fails, only users in that zone are affected and we have users spread over 3 zones.
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%