I'm suggesting you haven't read enough before replying, just like I did on my first comment. See "Myrocks" as an example of what the first user meant with lmdb. Replace "mysql -> redis" and "rocksdb -> lmdb".
I'm looking for a standard, well-known, drop-in product - that's what Redis is, that's why persistent storage support in Redis is interesting. If I have to search up some combination thing then it's already a non-starter.