Failed to start Docker Application Container Engine

Question

Because I'm new to Docker, I don't know much about it. I used the command to restart the Docker service.

service docker restart

I did a CTL+C because the command was taking too long. Now I'm unable to run the Docker daemon. The output of any docker command is as follows:

Cannot connect to the Docker daemon. Is the docker daemon running on this host?

I attempted to launch the Docker daemon using

systemctl start docker

However, it produces the following results:

Job for docker.service failed because the control process exited with error code. See "systemctl status docker.service" and "journalctl -xe" for details.

The command output

**systemctl status docker.service**

`● docker.service - Docker Application Container Engine
   Loaded: loaded (/usr/lib/systemd/system/docker.service; enabled; vendor preset: disabled)
  Drop-In: /etc/systemd/system/docker.service.d
           └─docker.conf, http-proxy.conf, https-proxy.conf
   Active: failed (Result: exit-code) since Mon 2018-03-05 17:17:54 IST; 2min 23s ago
     Docs: https://docs.docker.com
  Process: 11331 ExecStart=/usr/bin/dockerd --graph=/app/dockerRT (code=exited, status=1/FAILURE)
 Main PID: 11331 (code=exited, status=1/FAILURE)
   Memory: 76.9M
   CGroup: /system.slice/docker.service
           └─4593 docker-containerd-shim 3bda33eac892d14adda9f3b1fc8dc52173e26ce60ca949075227d903399c7517 /var/run/docker/libcontainerd/3bda33eac892d14adda9f3b1fc8dc52173e26c...
Mar 05 17:17:05 hj-fsbfsd9761.persistent.co.in systemd[1]: Starting Docker Application Container Engine...
Mar 05 17:17:05 hj-fsbfsd9761.persistent.co.in dockerd[11331]: time="2018-03-05T17:17:05.126009059+05:30" level=info msg="libcontainerd: new containerd process, pid: 11337"
Mar 05 17:17:06 hj-fsbfsd9761.persistent.co.in dockerd[11331]: time="2018-03-05T17:17:06.346599571+05:30" level=warning msg="devmapper: Usage of loopback devices is ...section."
Mar 05 17:17:10 hj-fsbfsd9761.persistent.co.in dockerd[11331]: time="2018-03-05T17:17:10.889378989+05:30" level=warning msg="devmapper: Base device already exists an...ignored."
Mar 05 17:17:10 hj-fsbfsd9761.persistent.co.in dockerd[11331]: time="2018-03-05T17:17:10.976695025+05:30" level=info msg="[graphdriver] using prior storage driver \"...mapper\""
Mar 05 17:17:54 hj-fsbfsd9761.persistent.co.in dockerd[11331]: time="2018-03-05T17:17:54.312812069+05:30" level=fatal msg="Error starting daemon: timeout"
Mar 05 17:17:54 hj-fsbfsd9761.persistent.co.in systemd[1]: docker.service: main process exited, code=exited, status=1/FAILURE
Mar 05 17:17:54 hj-fsbfsd9761.persistent.co.in systemd[1]: **Failed to start Docker Application Container Engine.**
Mar 05 17:17:54 hj-fsbfsd9761.persistent.co.in systemd[1]: Unit docker.service entered failed state.
Mar 05 17:17:54 hj-fsbfsd9761.persistent.co.in systemd[1]: docker.service failed.
Hint: Some lines were ellipsized, use -l to show in full.

journalctl -xe loop: Write error at byte offset 63585648640, length 4096.

How can I be able to start Docker without losing any containers or reverting to old settings?