Cloned from launchpad blueprint https://blueprints.launchpad.net/nova/+spec/shutdown-release-resource.

Description:

As we know,When the  VM is in shutdown status , nova host resource manager still consider it  occupy the host's resources. In some situations,  Host's resource should be controled by users .
In that case,there is a serious problem that if boot a vm in shundown status and the host doesn't have enough resource,the vm will in error status. So, a migrate operator is needed here.

Goals: 
1. Add a shutdown resouce release feature to nova-compute.
2. Add a migrate operate before start a vm , when host's resouce is not enough .


Specification URL (additional information):

None