Open Stack

Currently in nova we have the "vm_state", which according to the code 
comments is supposed to represent "a VM's current stable (not 
transition) state", or "what the customer expect the VM to be".

However, we then added in an ERROR state.  How does this possibly make 
sense given the above definition?  Which customer would ever expect the 
VM to be in an error state?

Given this, I wonder whether it might make sense to formally distinguish 
between the expected/desired state (i.e. the state that the customer 
wants the VM to be in), and the actual state (i.e. the state that nova 
thinks the VM is in).

This would more easily allow for recovery actions, since if the actual 
state changes to ERROR (or similar) we would still have the 
expected/desired state available for reference when trying to take 
recovery actions.

Thoughts?

Chris