Comment 0 for bug 1737676

The affinity/anti-affinity checks of Nova do not work correctly since Pike [1]. Upcalls from the computes to the scheduler (or other control services) cannot occur in deployments with multiple (v2) cells [2]. The affinity/anti-affinity checks have to be enabled for instance reservation.

[1] https://docs.openstack.org/releasenotes/nova/pike.html#id10
[2] https://docs.openstack.org/nova/latest/user/cellsv2-layout.html#operations-requiring-upcalls