These questions are independently created for study purposes. They are not official AWS exam questions, actual exam questions, leaked questions, or exam dumps.
SAA-045
A commercial database running on EC2 constantly demands around 30,000 IOPS and needs to keep latency variation small. Which configuration is the most appropriate for meeting this requirement with a single EBS volume?
Choices
Explanation and answer
Read the explanation and correct answer (spoiler — try answering first)
Correct answer: B. Create an io2 volume and provision the required IOPS
Explanation
The IOPS limit for general purpose SSD (gp2 / gp3) is 16,000 IOPS per volume. To sustain 30,000 IOPS on a single volume, you need io2 (or io2 Block Express), which is Provisioned IOPS SSD. io2 provides consistent low latency and high durability.
Per-choice explanations
A. Create a gp3 volume and provision 30,000 IOPS
Incorrect. gp3 lets you provision IOPS and throughput independently of capacity, but the limit is 16,000 IOPS per volume. You cannot specify 30,000 IOPS.
B. Create an io2 volume and provision the required IOPS
Correct. io2 lets you provision IOPS and delivers performance well above 16,000 IOPS on a single volume with consistent low latency.
C. Create an st1 (Throughput Optimized HDD) volume
Incorrect. st1 is HDD-based and optimized for large-block sequential reads and writes. It is not suited to workloads with heavy random I/O such as databases.
D. Create a large gp2 volume and use the baseline IOPS that grows in proportion to capacity
Incorrect. gp2 IOPS grow at 3 IOPS per GiB of capacity, but the maximum is 16,000 IOPS. Increasing capacity never reaches 30,000 IOPS, and you cannot specify IOPS independently of capacity.
Practical Use
Amazon EBS volume types divide broadly into SSD-based and HDD-based. SSD types are for workloads where random I/O (IOPS) matters and include general purpose SSD gp2 / gp3 and Provisioned IOPS SSD io1 / io2 / io2 Block Express. HDD types are for workloads where sequential throughput matters and include Throughput Optimized HDD st1 and Cold HDD sc1. As a broad rule, databases and transaction processing use SSD types, while big data processing and log processing use HDD types. The difference between gp2 and gp3 is how performance is determined. gp2 ties its baseline of 3 IOPS per GiB to capacity and depends on a burst bucket at small sizes. gp3 has a baseline of 3,000 IOPS / 125 MiB/s and lets you provision additional IOPS and throughput independently of capacity, so you no longer need to inflate capacity just for performance, and it is cheaper than gp2 at the same capacity. However, both gp2 and gp3 have a per-volume IOPS limit of 16,000, and requirements above that call for the io2 family. io2 supports Provisioned IOPS and offers higher durability than general purpose SSD, and io2 Block Express supports even higher IOPS and throughput. Note that EBS performance is also limited by the EC2 instance's EBS bandwidth, not just by the volume, so EBS-optimized instances and an appropriate instance size are prerequisites. On SAA-C03, questions that present a required IOPS number and ask you to select the appropriate volume type are a staple. The basic axis is to split between gp3 and io2 at the general purpose SSD limit of 16,000 IOPS, and phrases such as "consistent low latency" or "mission-critical database" make io2 more likely. Conversely, "large sequential throughput," "log processing," or "cost focused" make st1 / sc1 the correct answer.