playground
Cache Hit Ratios & the Thundering Herd
A cache absorbs its hit ratio; the origin eats the misses. The origin here sustains 5,000 rps. Find the hit ratio where the origin survives — then flush the cache and watch the herd arrive.
cache warmth 100%
origin sees 2,000 rps
dropped 0 rps
caching guidestep 1/3
→ Set traffic to 20k rps, then find the lowest hit ratio that keeps the origin healthy (its bar out of the red).
waiting for you to try it…
cache (100,000 rps cap)20%
20,000 rps in · serves 90%
origin database (5,000 rps cap)40%
2,000 rps of misses
The takeaway: a hit ratio is a claim about your workload, and the origin must survive the moments the claim is false — misses, cold starts, evictions. Size for the herd, not the average.
Read the caching lesson →