docker 启动报错，解决办法

• 一开始安装的docker1.13版本，后来想在该节点安装rancher，所以需要将docker版本降级。重装docker后启动docker遇到的问题如下：

[root@centos7-m02 files]# systemctl start docker
Job for docker.service failed because the control process exited with error code. See "systemctl status docker.service" and "journalctl -xe" for details.
[root@centos7-m02 files]# systemctl status docker.service
● docker.service - Docker Application Container Engine
   Loaded: loaded (/usr/lib/systemd/system/docker.service; enabled; vendor preset: disabled)
   Active: failed (Result: exit-code) since Tue 2018-11-20 11:51:21 CST; 5s ago
     Docs: https://docs.docker.com
  Process: 3844 ExecStart=/usr/bin/dockerd (code=exited, status=1/FAILURE)
 Main PID: 3844 (code=exited, status=1/FAILURE)

Nov 20 11:51:20 centos7-m02 systemd[1]: Starting Docker Application Container Engine...
Nov 20 11:51:20 centos7-m02 dockerd[3844]: time="2018-11-20T11:51:20.633475528+08:00" level=info ...850"
Nov 20 11:51:21 centos7-m02 dockerd[3844]: time="2018-11-20T11:51:21.640127510+08:00" level=error...ted"
Nov 20 11:51:21 centos7-m02 dockerd[3844]: Error starting daemon: error initializing graphdriver:...rted
Nov 20 11:51:21 centos7-m02 systemd[1]: docker.service: main process exited, code=exited, status=...LURE
Nov 20 11:51:21 centos7-m02 systemd[1]: Failed to start Docker Application Container Engine.
Nov 20 11:51:21 centos7-m02 systemd[1]: Unit docker.service entered failed state.
Nov 20 11:51:21 centos7-m02 systemd[1]: docker.service failed.
Hint: Some lines were ellipsized, use -l to show in full.

• 通过网上搜索解决办法如下：

rm /var/lib/docker/aufs -rf
rm /var/lib/docker -fr
#重启docker 进程
systemctl start docker

参考链接：

https://stackoverflow.com/questions/33357824/prior-storage-driver-aufs-failed-driver-not-supported-error-starting-daemon