What the exam asks
- Fix slow or failing uploads (large objects, long distances, unreliable links).
- Fix throttling (HTTP 503 Slow Down, KMS throttling) at high request rates.
- Choose S3 Express One Zone when compute needs single-digit-millisecond object access.
- Give global clients one endpoint in front of buckets in several Regions.
- Pick the right Storage Gateway type for a hybrid requirement.
Core ideas
Request-rate scaling by prefix
S3 supports at least 3,500 PUT/COPY/POST/DELETE and 5,500 GET/HEAD requests per second per partitioned prefix, and a bucket can have any number of prefixes. To go faster, spread keys across more prefixes (for example sensor-17/2026/... instead of everything under 2026-09-28/) and send requests in parallel. When load jumps suddenly, S3 may return 503 Slow Down while it scales. Clients should retry with exponential backoff.
Moving big objects fast
| Technique | What it does | Use when |
|---|---|---|
| Multipart upload | Splits an object into parts that upload in parallel, in any order, and are retried individually | Recommended from about 100 MB, required above 5 GB (the single PUT limit) |
| Byte-range fetches | Parallel GETs for different byte ranges of one object | Faster large downloads, or reading only part of a file (such as a header) |
| Transfer Acceleration | Clients upload to the nearest CloudFront edge location, and data then crosses the AWS backbone to the bucket | Clients far from the bucket’s Region, sending larger objects. Uses a separate accelerate endpoint |
| Multi-Region Access Points | One global endpoint that routes each request to the closest bucket over the AWS network, with failover controls |