Memory & CPU. We knew we'd be running into both eventually - without adding additional redis instances (memory growing way faster than CPU usage in this specifi

Memory & CPU. We knew we'd be running into both eventually - without adding additional redis instances (memory growing way faster than CPU usage in this specific scenario). When it was initially built, it was basically a bunch of redis lua scripts to handle updating the data - on redis configured in master/slave managed by sentinels. Given the nature of the data too, only the data for active users would be hot - but users that were inactive would have stuck around in memory needlessly. Our new system keeps only the hot set of users in memory. We also built it to transparently migrate users from redis to cassandra when they were accessed.