Check inside the droplet and find out why the directories are large.

sudo df -kh gave me:

Filesystem Size Used Avail Use% Mounted on
udev 488M 0 488M 0% /dev
tmpfs 100M 3.2M 97M 4% /run
/dev/vda1 29G 11G 19G 38% /
tmpfs 497M 0 497M 0% /dev/shm
tmpfs 5.0M 0 5.0M 0% /run/lock
tmpfs 497M 0 497M 0% /sys/fs/cgroup
/dev/vda15 105M 3.4M 102M 4% /boot/efi
tmpfs 100M 0 100M 0% /run/user/1000

My bad, i had nothing to do with Redis.

I had a bad configuration so an error log where huge.

Sorry guys