"9) Active memory defragmentation. Redis is able to defragment the memory while online..."

I'm so amazed that this is a thing.

Memory fragmentation is largely related to the allocator you're using (ie: glibc malloc, jemalloc, tcmalloc) and previously it was up to the OS to manage this (ie: freeing up unused memory).

Now with active memory defragmentation things are a bit more pleasant, specifically with high delete load actually freeing up unused memory in a timely manner without impacting performance too much.

Previously, to fully recover unused memory, you would have to restart the Redis server. Obviously this is not feasible but when Redis is using >50% more memory on a 120GB machine than it should then you will have to consider this an occasional housekeeping option -- now, as mentioned, this ridiculous task is no longer necessary.

120GB on a single thread, yeah. Redis has been abused for quite some time but 120GB is way out of reasonable reach for current CPU arch if you use a single core only (even if you switch off hyper threading)

Call me a slowpoke, but I wasn't aware that Redis was single core!