not sure whether it will helpful , FYI

The primary differences between Nova’s host aggregates and placement
aggregates are the following:
      In Nova, a host aggregate associates a nova-compute service with
      other nova-compute services. Placement aggregates are not specific to
      a nova-compute service and are, in fact, not compute-specific at all.
      A resource provider in the Placement API is generic, and placement
      aggregates are simply groups of generic resource providers. This is
      an important difference especially for Ironic, which when used with
      Nova, has many Ironic baremetal nodes attached to a single
      nova-compute service. In the Placement API, each Ironic baremetal
      node is its own resource provider and can therefore be associated to
      other Ironic baremetal nodes via a placement aggregate association.
      In Nova, a host aggregate may have metadata key/value pairs attached
      to it. All nova-compute services associated with a Nova host
      aggregate share the same metadata. Placement aggregates have no such
      metadata because placement aggregates only represent the grouping of
      resource providers. In the Placement API, resource providers are
      individually decorated with traits that provide qualitative
      information about the resource provider.
      In Nova, a host aggregate dictates the availability zone within which
      one or more nova-compute services reside. While placement aggregates
      may be used to model availability zones, they have no inherent
      concept thereof.

Best Regards!

Kevin (Chen) Ji 纪 晨

Engineer, zVM Development, CSTL
Notes: Chen CH Ji/China/IBM@IBMCN   Internet:
Phone: +86-10-82451493
Address: 3/F Ring Building, ZhongGuanCun Software Park, Haidian District,
Beijing 100193, PRC

From:   Jeffrey Zhang <>
To:     OpenStack Development Mailing List
Date:   05/25/2018 11:34 AM
Subject:        [openstack-dev] [nova] nova aggregate and nova placement api

Recently, i am trying to implement a function which aggregate nova
rather than nova compute host. But seems nova only aggregate nova-compute

On the other hand, since Ocata, nova depends on placement api which
aggregating resource providers. But nova-scheduler doesn't use this feature

So  is there any better way to solve such issue? and is there any plan
make nova legacy aggregate and placement api aggregate cloud work together?

Jeffrey Zhang
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