SAP-C02 Question #9: Real Exam Question with Answer & Explanation

Question

An ecommerce website running on AWS uses an Amazon RDS for MySQL DB instance with General Purpose SSD storage. The developers chose an appropriate instance type based on demand, and configured 100 GB of storage with a sufficient amount of free space. The website was running smoothly for a few weeks until a marketing campaign launched. On the second day of the campaign, users reported long wait times and time outs. Amazon CloudWatch metrics indicated that both reads and writes to the DB instance were experiencing long response times. The CloudWatch metrics show 40% to 50% CPU and memory utilization, and sufficient free storage space is still available. The application server logs show no evidence of database connectivity issues. What could be the root cause of the issue with the marketing campaign?

Options

• AIt exhausted the I/O credit balance due to provisioning low disk storage during the setup phase.
• BIt caused the data in the tables to change frequently, requiring indexes to be rebuilt to optimize
• CIt exhausted the maximum number of allowed connections to the database instance.
• DIt exhausted the network bandwidth available to the RDS for MySQL DB instance.

Explanation

When using General Purpose SSD storage, your DB instance receives an initial I/O credit balance of 5.4 million I/O credits. This initial credit balance is enough to sustain a burst performance of 3,000 IOPS for 30 minutes. https://aws.amazon.com/blogs/database/how-to-use-cloudwatch-metrics-to-decide-between- general-purpose-or-provisioned-iops-for-your-rds-database/

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