Node Resource Consolidation

Problem description

In the edge computing system, the edge nodes are distributed in different locations. Although the total number of edge nodes may be large, the number of edge nodes in each location is limited, so the resources(VCPU, memory) are limited. An application scenario is to dynamically create VM(application) processing service. After the processing is complete, the VM is deleted and the resource is released. During this process(creating and deleting VM on different nodes), resource fragments are generated. For example, if two nodes each have two free VCPUs, even if the total VCPUs is enough, creating a VM with four VCPUs will still fail.

Use Cases

As a Watcher user, I wish Watcher provides a strategy which can eliminate resource fragmentation by consolidating resources on nodes.

Proposed change

  • Add a new strategy: Node Resource Consolidation

  • One input parameter: host_choice(specify/auto). This parameter determines how to select the server migration destination node. The value auto means that Nova schedular selects the destination node, and specify means the strategy specifies the destination. The default value is auto.

  • The algorithm of this strategy:

    • Caculating the used resources of compute nodes

    • Sorting compute nodes by the used resources percent

    • Dividing compute nodes into source group and destination group. The process: For sorted compute nodes, from the one that uses least resources, if all servers can be migrated to other compute nodes, we put this node into source group, and other nodes into destination group. repeating this process until all compute nodes are placed in the source or destination group. For continuous audit, if there is server that had failed during previous actionplan, we should put this compute node to the destination group.

    • Creating strategy solution: If the parameter host_choice is auto, creating a migration action for each VM in the source group and compute nodes in source should be disabled before server migration and be enabled after finishing the migration. If the parameter host_choice is specify, the nodes in the destination group are sorted by free resources. Then, for each VM on the source node, select a node that is most suitable for the VM from the destination group as the destination node of the migration. Repeat this process (reordering the destination group by free resources each time), until all VMs have destination or there is insufficient resources.



Data model impact


REST API impact


Security impact


Notifications impact


Other end user impact


Performance Impact


Other deployer impact


Developer impact




Primary assignee:


Work Items

  • Add a new parameter audit to the method do_execute of strategy.

  • Add the new strategy.




Unit and functional test are needed.

Documentation Impact

Add docs on how to use this strategy.





Release Name