Reconfigure rate-limits for Nova
Chapter 1. General Deployment Steps

Please reconfigure rate-limits to at least 500-1000 hits per minute.

API calls rate limits could be configured using this manual or by disabling ratelimits in the /etc/nova/api-paste.ini file.

                ...
                [composite:openstack_compute_api_v2]
                use = call:nova.api.auth:pipeline_factory
                #noauth = faultwrap sizelimit noauth ratelimit osapi_compute_app_v2
                #keystone = faultwrap sizelimit authtoken keystonecontext ratelimit osapi_compute
                noauth = faultwrap sizelimit noauth osapi_compute_app_v2
                keystone = faultwrap sizelimit authtoken keystonecontext osapi_compute_app_v2
                keystone_nolimit = faultwrap sizelimit authtoken keystonecontext osapi_compute_ap
                ...