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A global e-commerce company uses Azure Kubernetes Service (AKS) for its critical applications. They have defined a Service Level Objective (SLO) of 99.9% availability for their primary payment processing service over a 30-day period. Currently, the service has experienced 15 minutes of downtime within the first 10 days of the current period. What is the remaining error budget in minutes for the rest of the 30-day period?
- A29.2 minutes
- B28.2 minutes
- C57.6 minutes
- D43.2 minutes
Show answer & explanationAnswer & explanation
Correct answer: D. 43.2 minutes
The total allowed downtime for 99.9% availability over 30 days is 43.2 minutes. Since 15 minutes of downtime has already occurred, the remaining error budget is 43.2 - 15 = 28.2 minutes. The question asks for the remaining error budget for the *rest* of the 30-day period, which implies the total budget minus consumed budget, not the budget for the remaining days.
Why the other options are wrong
- A. Incorrect calculation. This would be 43.2 - 14, which is not 15 minutes.
- B. This is the correct calculation: (Total allowed downtime - consumed downtime).
- C. Incorrect calculation, potentially mixing up availability percentages or timeframes.
Error Budget Calculation
The maximum amount of time a system can be unavailable or perform poorly without violating its Service Level Objective (SLO).
- Calculated as (100% - SLO%) * total period duration.
- Represents the acceptable amount of 'bad' performance or downtime.
- Consumed when the service deviates from its SLO.
Memory trick: Error Budget: It's your 'downtime allowance' for the month.