Performance Cost Optimization & Resource Efficiency Questions

Approach

Two very different access patterns share one storage bill: thumbnails are read constantly but are tiny, originals are large but almost never read again after day one. Design around that asymmetry instead of applying one policy to both.

Strategy

• Thumbnails: keep in standard (hot) storage, and put a CDN (content delivery network, a caching layer close to users) in front of them with a long cache TTL (time-to-live). Since they're small and requested constantly, the CDN absorbs most of the read traffic, keeping origin storage cost and request cost low even though the tier itself is the expensive one.
• Originals: transition to a cheaper, infrequent-access class after a short buffer (a couple of days, not day one, since users often edit or delete a fresh upload and an early transition can trigger a minimum-storage-duration charge), then to an archive-class tier after a longer window, since the question states they're "almost never read again" past the first day.

Worked example

At 10 million images/month, average 4 MB originals and 50 KB thumbnails: originals total about 39,060 GB/month, thumbnails about 477 GB/month, so originals are roughly 80x the stored bytes even though thumbnails get nearly all the traffic. At an illustrative $0.023/GB-month, leaving originals in standard storage costs about $898/month per monthly cohort; moving them to an archive class at an illustrative $0.004/GB-month cuts that to about $156/month, a saving near $742/month (about 83%) per cohort, compounding every month new uploads land. Thumbnails, by contrast, cost only about $11/month even fully hot, because they're small; there's no real saving available there, which is exactly why they're not worth tiering down.

Trade-offs

• Archiving originals adds retrieval latency and a retrieval fee for the rare user who wants their full-resolution download; that's an acceptable trade given how rarely it happens, but the product needs a "this may take a moment" state for that path.
• An alternative or complementary lever is re-encoding originals to a smaller lossy format once they're old enough that print-quality is unlikely to matter, trading some quality for less-than-linear byte reduction; worth evaluating if archive-tier savings alone aren't enough, but it's a one-way, quality-losing move, so treat it separately and more cautiously than a reversible storage-class transition.