watcher/doc/source/strategies/workload_balance.rst

Workload Balance Migration Strategy

Synopsis

display name: Workload Balance Migration Strategy

goal: workload_balancing

watcher.decision_engine.strategy.strategies.workload_balance.WorkloadBalance

Metrics

The workload_balance strategy requires the following metrics:

metric	service name	plugins	unit	comment
cpu	ceilometer	none	percentage	CPU of the instance. Used to calculate the threshold
memory.resident	ceilometer	none	MB	RAM of the instance. Used to calculate the threshold

Note

* The parameters above reference the instance CPU or RAM usage, but the threshold calculation is based of the CPU/RAM usage on the hypervisor. * The RAM usage can be calculated based on the RAM consumed by the instance, and the available RAM on the hypervisor. * The CPU percentage calculation relies on the CPU load, but also on the number of CPUs on the hypervisor. * The host memory metric is calculated by summing the RAM usage of each instance on the host. This measure is close to the real usage, but is not the exact usage on the host.

Cluster data model

Default Watcher's Compute cluster data model:

watcher.decision_engine.model.collector.nova.NovaClusterDataModelCollector

Actions

Default Watcher's actions:

action	description
migration	watcher.applier.actions.migration.Migrate

Planner

Default Watcher's planner:

watcher.decision_engine.planner.weight.WeightPlanner

Configuration

Strategy parameters are:

parameter	type	default value	description
metrics	String	instance_cpu_usage	Workload balance base on cpu or ram utilization. Choices: ['instance_cpu_usage', 'instance_ram_usage']
threshold	Number	25.0	Workload threshold for migration. Used for both the source and the destination calculations. Threshold is always a percentage.
period	Number	300	Aggregate time period of ceilometer
granularity	Number	300	The time between two measures in an aggregated timeseries of a metric. This parameter is only used with the Gnocchi data source, and it must match to any of the valid archive policies for the metric.

Efficacy Indicator

None

Algorithm

For more information on the Workload Balance Migration Strategy please refer to: https://specs.openstack.org/openstack/watcher-specs/specs/mitaka/implemented/workload-balance-migration-strategy.html

How to use it ?

Create an audit template using the Workload Balancing strategy.

$ openstack optimize audittemplate create \
  at1 workload_balancing --strategy workload_balance

Run an audit using the Workload Balance strategy. The result of the audit should be an action plan to move VMs from any host where the CPU usage is over the threshold of 26%, to a host where the utilization of CPU is under the threshold. The measurements of CPU utilization are taken from the configured datasouce plugin with an aggregate period of 310.

$ openstack optimize audit create -a at1 -p threshold=26.0 \
        -p period=310 -p metrics=instance_cpu_usage

Run an audit using the Workload Balance strategy to obtain a plan to balance VMs over hosts with a threshold of 20%. In this case, the stipulation of the CPU utilization metric measurement is a combination of period and granularity.

$ openstack optimize audit create -a at1 \
       -p granularity=30 -p threshold=20 -p period=300 \
       -p metrics=instance_cpu_usage --auto-trigger

External Links

None.