LRU evicts durable keys
Your Redis cluster stores two kinds of keys: ephemeral cache entries (with TTLs) and a set of *durable* keys the team treats as a small system-of-record (feature flags, per-tenant config, in-flight idempotency tokens) that are written with no TTL. Since a traffic ramp this week, on-call reports sporadic 'config not found' and double-charged orders. Dashboards: Redis memory sits pinned at maxmemory, `evicted_keys` is climbing steadily, hit rate dropped. Context: the cluster's `maxmemory-policy` is `allkeys-lru`. How do you triage, stop the data loss, and recover?
What a strong answer looks like
Stop the bleeding first (mitigate), then form hypotheses from real signals. Separate root cause from symptom, communicate status as you go, and close with what prevents a repeat.
0:00 of about 35 min
Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.
Run or narrate your approach, then ask the coach.