[Redis OOM runbook]: check INFO memory for used_memory_human vs maxmemory_human and evicted_keys. Run --bigkeys to find the culprits: unbounded session caches, job queues with dead consumers, or objects over 1MB. Emergency relief: flush non-critical cache keys that rebuild, or raise maxmemory temporarily. Do not restart Redis unless forced: it causes a full cache cold start. After relief, find the growth inflection: a recent deploy that changed TTLs or added key patterns.

Context: 'OOM command not allowed when used memory > maxmemory' means find the memory hog, not just raise the limit.