(Disclaimer: I'm a Prometheus author.) Chunks are only written to that one file per time series once they are complete. Depending on their compression behavior

(Disclaimer: I'm a Prometheus author.) Chunks are only written to that one file per time series once they are complete. Depending on their compression behavior, they will contain at least 64 samples, but usually a couple of hundreds. Even then, chunks are just queued for disk persistence. The storage layer operates completely from RAM, only has to swap in chunks if it was evicted from memory previously. Obviously, if you consistently create more sample data than your disk can write, the persist queue will back up at some point and Prometheus will throttle ingestion.