Nova doesn't have (yet) in its scope to manage instance allocations and that really looks like a new feature that should be discussed in a spec.
http://docs.openstack.org/developer/nova/process.html#how-do-i-get-my- code-merged ** Changed in: nova Status: New => Opinion ** Changed in: nova Importance: Undecided => Wishlist -- You received this bug notification because you are a member of Yahoo! Engineering Team, which is subscribed to OpenStack Compute (nova). https://bugs.launchpad.net/bugs/1630929 Title: Affinity instance slot reservation Status in OpenStack Compute (nova): Opinion Bug description: Currently ServerGroupAffinityFilter schedules all instances of a group on the same host, but it doesn't reserve any slots for future instances on the host. Example: max_instances_per_host=10 quota_server_group_members=5 When user_1 would spawns 3 instances with affinity server group policy, all the instances will be scheduled on the same host (host_A). If user_2 also spawns instances and they are placed on host_A, quota of max_instances_per_host will be reached, so user_1 can not add 2 new instances to the same server group and error "No valid host found" will be returned. My proposition is to add new parameters to nova.conf to configure ServerGroupAffinityFilter: - enable_slots_reservation (Boolean) - reserved_slots_per_instance (-1 will count difference between max_instances_per_host and quota_server_group_members ; values bigger than 0 will reserve the indicated number of ports per group) Nova scheduler checks if on a host there are any instances with affinity policy and based on that, it counts available slots. To manage notifications about this bug go to: https://bugs.launchpad.net/nova/+bug/1630929/+subscriptions -- Mailing list: https://launchpad.net/~yahoo-eng-team Post to : yahoo-eng-team@lists.launchpad.net Unsubscribe : https://launchpad.net/~yahoo-eng-team More help : https://help.launchpad.net/ListHelp