start another docker machine

# start another docker machine

# create a new docker machine
docker-machine create -d virtualbox --virtualbox-memory 2048 --virtualbox-disk-size 204800 my_new_machine

# replace my_new_machine
docker-machine start my_new_container
eval $($DOCKER_MACHINE env my_new_container --shell=bash)
docker-machine ssh my_new_container