# Node Resource Consolidation Strategy

## Synopsis

display name: `Node Resource Consolidation Strategy`

goal: `Server Consolidation`

> consolidating resources on nodes using server migration

> Description

> This strategy checks the resource usages of compute nodes, if the used resources are less than total, it will try to migrate server to consolidate the use of resource.

> Requirements

> - You must have at least 2 compute nodes to run this strategy.

> - Hardware: compute nodes should use the same physical CPUs/RAMs

> Limitations

> - This is a proof of concept that is not meant to be used in production

> - It assume that live migrations are possible

> Spec URL

> http://specs.openstack.org/openstack/watcher-specs/specs/train/implemented/node-resource-consolidation.html

## Requirements

None.

### Metrics

None

### Cluster data model

Default Watcher’s Compute cluster data model:

> Nova cluster data model collector

> The Nova cluster data model collector creates an in-memory representation of the resources exposed by the compute service.

### Actions

Default Watcher’s actions:

> action | description
> --- | ---

> `migration`

> Migrates a server to a destination nova-compute host

> This action will allow you to migrate a server to another compute destination host. Migration type ‘live’ can only be used for migrating active VMs. Migration type ‘cold’ can be used for migrating non-active VMs as well active VMs, which will be shut down while migrating.

> The action schema is:

>     schema = Schema({
>      'resource_id': str,  # should be a UUID
>      'migration_type': str,  # choices -> "live", "cold"
>      'destination_node': str,
>      'source_node': str,
>     })

> The resource_id is the UUID of the server to migrate. The source_node and destination_node parameters are respectively the source and the destination compute hostname (list of available compute hosts is returned by this command: `nova service-list --binary nova-compute`).

> Note

> Nova API version must be 2.56 or above if destination_node parameter is given.

> `change_nova_service_state`

> Disables or enables the nova-compute service, deployed on a host

> By using this action, you will be able to update the state of a nova-compute service. A disabled nova-compute service can not be selected by the nova scheduler for future deployment of server.

> The action schema is:

>     schema = Schema({
>      'resource_id': str,
>      'state': str,
>      'disabled_reason': str,
>     })

> The resource_id references a nova-compute service name (list of available nova-compute services is returned by this command: `nova service-list --binary nova-compute`). The state value should either be ONLINE or OFFLINE. The disabled_reason references the reason why Watcher disables this nova-compute service. The value should be with watcher_ prefix, such as watcher_disabled, watcher_maintaining.

### Planner

Default Watcher’s planner:

> Weight planner implementation

> This implementation builds actions with parents in accordance with weights. Set of actions having a higher weight will be scheduled before the other ones. There are two config options to configure: action_weights and parallelization.

> Limitations

> - This planner requires to have action_weights and parallelization configs tuned well.

## Configuration

Strategy parameters are:

parameter | type | default Value description
--- | --- | ---
`host_choice` | String | The way 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.

## Efficacy Indicator

None

## Algorithm

For more information on the Node Resource Consolidation Strategy please refer to: https://specs.openstack.org/openstack/watcher-specs/specs/train/approved/node-resource-consolidation.html

## How to use it ?

    $ openstack optimize audittemplate create \
      at1 server_consolidation \
      --strategy node_resource_consolidation

    $ openstack optimize audit create \
      -a at1 -p host_choice=auto

## External Links

None.

this page last updated: 2026-05-26 14:30:00

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