A high-transaction OLTP database on RDS for MySQL needs a sustained 40,000 IOPS with consistent single-digit millisecond latency, independent of how much data is stored. Which volume type should be chosen?
Show answer and explanation
Answer: A
Provisioned IOPS volumes let you specify an IOPS level separately from capacity, so a relatively small volume can still deliver a high, predictable rate, and io2 adds higher durability than io1. That suits a write-heavy OLTP workload whose I/O demand does not scale with data size. The volume keeps its provisioned performance rather than relying on burst credits.
Why the other options are wrong
- B. gp3 also decouples IOPS from volume size, but its maximum is 16,000 IOPS per volume, well below the stated requirement.
- C. Magnetic volumes are not available for new RDS instances and have high latency and low IOPS.
- D. st1 is HDD-backed and tuned for large sequential throughput. RDS does not offer it as a database volume type, and it would be wrong for random OLTP I/O in any case.
Exam tip. Above roughly 16,000 IOPS on RDS, move from gp3 to io1 or io2.