Can't create instance, no valid host was found, nova-compute is not running
I installed openstack via devstack, branch juno on my Ubuntu 12.04(not VM).
When I was trying to launch an instance, I received the error message "No valid host was found. There are not enough hosts available".
After googling a while, I found that someone has encountered exactly the same problem in this https://www.mail-archive.com/openstack@lists.openstack.org/msg09810.html (thread).
Although the thread did not come with a final solution, it mentions that the missing of nova-compute could result in such a problem. And running the command "nova-manage service list" shows that nova-compute is indeed missing.
So I was trying to enable the nova-compute by the command "nova-manage service enable --host=xxx --service=nova-compute". However, I ended with an error message "error: Could not find binary nova-compute on host xxx."
Now, I am stuck here. Could anyone shed some light on this? Thanks