Open Stack

Hi,

I've been working with OpenStack for a while now but I'm still a bit 
fuzzy on the precise meaning of some of the terminology.

It seems reasonably clear that a "node" is a computer running at least 
one component of an Openstack system.

However, "nova service-list" talks about the "host" that a given service 
runs on.  Shouldn't that be "node"?  Normally "host" is used to 
distinguish from "guest", but that doesn't really make sense for a 
dedicated controller node.

"nova show" reports "OS-EXT-SRV-ATTR:host" and 
"OS-EXT-SRV-ATTR:hypervisor_hostname" for an instance.  What is the 
distinction between the two and how do they relate to OpenStack "nodes" 
or the "host" names in "nova service-list"?

"nova hypervisor-list" uses the term "hypervisor hostname", but "nova 
hypervisor-stats" talks about "compute nodes".  Is this distinction 
accurate or should they both use the hypervisor terminology?  What is 
the distinction between hypervisor/host/node?

"nova host-list" reports "host_name", but seems to include all services. 
  Does "host_name" correspond to host, hypervisor_host, or node?  And 
just to make things interesting, the other "nova host-*" commands only 
work on compute hosts, so maybe "nova host-list" should only output info 
for systems running nova-compute?


Thanks,
Chris