As more and more data is cached memory usage increases - 5TB/2.5m objects when fully cached will consume big amount of both disk space and memory. Even if you have enough disk space it might be too much for your available memory.
I suggest you limit cache size by adding --vfs-cache-max-size 1000G to your mount command. Decrease/increase this value based on your observed memory usage.
Also please use some online translator when posting. E.g. https://translate.google.com/ - most people here do not speak mandarin.