Comment by NavinF

>appendfsync always: fsync every time new commands are appended to the AOF. Very very slow, very safe. Note that the commands are appended to the AOF after a batch of commands from multiple clients or a pipeline are executed, so it means a single write and a single fsync (before sending the replies).

https://redis.io/docs/management/persistence/

It's very slow, but if you really want to wait for fsync before replying, it can do that.