Redis Evictions Mean Memory Policy Is Affecting Data

Redis can remain responsive while silently evicting keys because the configured memory limit has been reached. On hserver the first signal I use for this question is increase(hserver_redis_evicted_keys_total[15m]). Eviction is a semantic event: depending on the service, it can mean normal cache behavior or lost session and queue state.

The important part is interpretation rather than collecting another graph. state-aware cache monitoring. That gives the metric a specific operational job instead of making it another number on a dashboard.

The practical control is straightforward: Alert on new evictions, know each Redis instance's role, and correlate with memory usage before changing eviction policy or capacity. This also gives me a repeatable check after deployments, exporter changes, or capacity tuning.

Repository evidence for this monitoring behavior is commit b65d5d4. I keep that reference with the note because a monitoring conclusion is stronger when the configuration and runtime decision that produced it can be inspected later.