Hi, I am looking at adding the option for the vmwareapi driver to expose the individual ESXi hosts. A compute-host would represent a cluster in vsphere, and each ESXi-host within a cluster would be a ComputeNode. The main question here is, how to handle a hypervisor initiated change of the compute-node and if the community is open to extending the compute-driver interface for such a use-case. The secondary one is, if there is interest in having the upstream vmwareapi driver getting this functionality. * What are we trying to solve by that? Our users are asking for that feature, because they want to know, if a payload of two VMs runs on the same physical host, as the performance characteristics are quite different. We also gain there from an operational and code perspective: - Nova would become aware of the actual resources per ESXi host instead of the aggregated ones. - Resources could also be more faithfully represented in the resource-tree (e.g., shared storage as an aggregate). - Capabilities, (cpu-flags, architecture,… ), Numa topology, and even small things like up-time can be faithfully reflected on a per-host basis. - The internal scheduling decisions in the driver for ephemeral storage and compute (for live-migration) can be handled by standard placement & nova scheduling. * Why do we need to change the driver interface? Main problem here is that VSphere might migrate a VM between two ESXi-hosts for various reasons. So, the driver would need a way to communicate such a change somehow. But even if we disable all kind of migrations on VMware side, we still need a way to migrate the VMs from the single compute-node for the whole cluster to the compute nodes for each individual ESXi-hosts. * Proposed Driver API Change The Compute-Manager is currently periodically polling the driver with ComputeDriver.get_info(self, instance, use_cache) which returns an InstanceInfo, which is essentially only the power-state. Adding two new optional fields to InstanceInfo could allow the driver to inform the manager about - the current compute-node - the compute-node the VM is migrated to This allows the Compute-Manager to take care of updating the node field and the resource-allocations accordingly. Additionally, we can notify the manager over Instance lifecycle events, allowing for a faster reflection of a compute-node change. The lifecycle events could be - EVENT_LIFECYCLE_COMPUTE_NODE_MIGRATION_STARTED - EVENT_LIFECYCLE_COMPUTE_NODE_MIGRATION_COMPLETED Or one could generalize the current life-migration events to include also such compute-node changes. I am looking forward for your feedback. Cheers, Fabian