SOA-C03 practice question: EBS performance and volume types

Monitoring, Logging, Analysis, Remediation, and Performance Optimization A free question from our original SOA-C03 practice exam. Try it, then open the answer to see why each option is right or wrong.

An esports league's stats database runs on a single 500 GiB gp2 EBS volume. During evening tournaments the workload needs about 4,000 IOPS for several hours. CloudWatch shows the volume's BurstBalance metric falling to zero each evening, after which latency rises sharply. The team wants to fix this without downtime and at the LOWEST cost. What should a CloudOps engineer do?

Choose one answer.

A. Use Elastic Volumes to change the volume to io2 with 4,000 provisioned IOPS while the instance keeps running.
B. Use Elastic Volumes to grow the gp2 volume to about 1,334 GiB so that its baseline rises to 4,000 IOPS.
C. Use Elastic Volumes to change the volume to gp3 and set 4,000 provisioned IOPS while the instance keeps running.
D. Use Elastic Volumes to change the volume to st1, which is designed for sustained large workloads at a lower price per GiB.

Show the answer and explanation

Answer: C

A. Wrong: io2 would deliver the IOPS without downtime, but it costs considerably more per GiB and per IOPS than gp3. It is not the lowest-cost fix for this workload. Learn more: Provisioned IOPS SSD volumes (opens in a new tab)
B. Wrong: gp2 gives 3 IOPS per GiB, so this size would reach the target. It means paying for 834 GiB of storage the database does not need, which costs more than gp3 with provisioned IOPS. Learn more: Modify a volume using Amazon EBS Elastic Volumes (opens in a new tab)
C. Right: Correct. gp3 gives a 3,000 IOPS baseline at any size, with extra IOPS provisioned separately, and has no burst credits. Elastic Volumes changes the type online, so this meets the need without downtime at low cost. Learn more: General Purpose SSD volumes (opens in a new tab)
D. Wrong: st1 is a throughput-optimized HDD volume for large sequential reads and writes. A database doing many small random I/O operations would perform far worse on it. Learn more: Throughput Optimized HDD and Cold HDD volumes (opens in a new tab)

Explanation

A gp2 volume earns 3 IOPS per GiB, so 500 GiB gives a 1,500 IOPS baseline and bursts above it only while credits last; a BurstBalance of zero is the sign. gp3 separates performance from size, with a 3,000 IOPS baseline and extra IOPS bought on their own, so it is usually the cheapest way to get sustained IOPS. Elastic Volumes makes the change while the volume stays in use.

SOA-C03 practice question: EBS performance and volume types

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