If the whole compute plane is down, it is not always obvious how to boot it up, because it can be subject to deadlock if evacuate attributes are set on every Compute Node. In this case, manual intervention is required. Specifically, the operator must manually choose one or more Compute Nodes to bootstrap the compute plane, and then run the attrd_updater -n evacuate -U no -N NODE command for each of those Compute Nodes to indicate that they do not require the resurrection process and can have their nova-compute start up straight away. Once these Compute Nodes are up, this breaks the deadlock allowing nova-evacuate to start. This way, any other nodes that require resurrection can be processed automatically. If no resurrection is desired anywhere in the cloud, then the attributes should be set to no for all nodes.