Prometheus storage.tsdb.retention.time, scrape_interval and remote_write for low-traffic cost control

Goal is to lower storage and resource consumption for a low-traffic Prometheus deployment by keeping only a short local window and offloading longer-term data.

The configuration involves --storage.tsdb.retention.time for local pruning, a coarser scrape_interval to reduce head block series churn, and remote_write to a separate store. Drop relabeling is also under consideration to remove high-cardinality labels at ingestion.

There is uncertainty about the interaction between local retention expiry and remote write delivery guarantees, and about the acceptable data granularity loss from a larger scrape interval for infrequent targets.

What is the effective data availability window when local retention is shorter than remote write buffering? How does scrape_interval interact with retention pruning for low-traffic series? Is there a documented permission boundary for drop relabeling that prevents accidental removal of metrics needed for remote write?