War Story: We Migrated From Memcached 1.6 to Redis 7.2 and Cut Cache Misses by 60%

At 3:17 AM on a Tuesday in Q3 2024, our p99 API latency hit 4.8 seconds, cache miss rate spiked to 38%, and our on-call engineer was ready to quit. We’d been running Memcached 1.6 as our primary cache for 7 years—this was the breaking point. Three months later, after migrating to Redis 7.2 with a cu