Docker Swarm with Overlay

Hi,

Server Version: 1.12.5
Storage Driver: overlay
 Backing Filesystem: extfs
Logging Driver: json-file
Cgroup Driver: cgroupfs

Docker Host : RedHat 7.2 Maipo
Docker Container Base : RedHat 7.2 Maipo

I am using docker swarm, there are 10 containers in my swarm. My docker overlay volume will increase 10GB every week even there is not new containers or images have been updated or created and I couldn’t find why and where the storage is gone.
It does not gradually increasing the storage space over 7 days. The increasing part only happened in 1-2 days then it will flat for a few days until the next occurrence.

Try with “docker ps -s” too, but the container size is just 100MB.
Try with “du -sh” in container level and the size of the container excluded the mounted volume is just 100MB++ only.
All the logs generated by the application on the container has been mounted to docker host level.

The only solution I have now is to kill my containers and delete the old containers to purge the “Exited” containers away so that I can maintain the available storage space.

Anyone facing this issue? Please enlighten me.