I have set maxmemory in redis.conf to 20G, but when I ran redis-cli,
inserting data with 15G, the memory consisting of virtual and physical
was always about 8G, why? Where was the remaining data? At the same
time, I checked the dump.rdb, whose size always ranged from 800M to
1.6G, and I searched in google which told me the lateset data replaced
old ones. If so, how should I do to avoid that situation?