Why the Linux total storage auto increase?

I had a Docker Image including a KVM and a windows.img of qcow2 format. And launched a container based on the Image, then I could connect to the windows by remote desktop connection.
Theoretically, running a container doesn’t take any storage, only when writing to windows can add storage in this case. But curiously, I did nothing in the windows, the total storage of Linux auto increase a lot (about 20GB) during the about four hours after windows booting up, and then the speed of the storage increasing slowed down.
What’s more, the windows.img file increased only 12GB, and the windows disk size didn’t change at all. After removing the container, the increased 20GB came back. I want to know why the total storage auto increased and where were the increased size.

  • Dokku server hosts two sites with TLD's, both domains are landing on only one app
  • php-fpm child process exited on signal 11
  • How to create a docker container out of existing project on Ubuntu
  • Marathon - do not redeploy app when return code = 0?
  • Updating a config file through docker-compose
  • Adding an ECS instance in AWS - where to set the cluster name
  • Cannot start docker after installation on Windows
  • Host as Pid namespace in Docker
  • Docker trusted build doesn't show up in search
  • Get host name/ip for Docker network
  • Different behaviour between docker-compose volume mount on OSX and Linux
  • Can't download python packages onto Docker image
  • Docker will be the best open platform for developers and sysadmins to build, ship, and run distributed applications.