Error running DeleteDevice dm_task_run failed
重启docker即可
Error starting daemon: error initializing graphdriver: \"/var/lib/docker\" contains several valid graphdrivers: devicemapper, overlay; Please cleanup or explicitly choose storage driver (-s <DRIVER>)
到/var/lib/docker根据情况，将下面的overlay或者devicemapper文件夹删掉即可。这种情况发生在使用采用dc/os安装后，原有的devicemapper模式修改成了overlay，但是docker同时只能支持一种存储模式。