devstack安装的openstack重启之后如何恢复

# screen session from a previous run of stack.sh.
TOP_DIR=`dirname $0`
# Import common functions in case the localrc (loaded via stackrc)
# uses them.
source $TOP_DIR/functions
source $TOP_DIR/stackrc
# if screenrc exists, run screen
if [[ -e $TOP_DIR/stack-screenrc ]]; then
    if screen -ls | egrep -q "[0-9].stack"; then
        echo "Attaching to already started screen session.."
        exec screen -r stack
    fi
    exec screen -c $TOP_DIR/stack-screenrc
fi
echo "Couldn't find $TOP_DIR/stack-screenrc file; have you run stack.sh yet?"
exit 1