Workload Balance Migration Strategy¶
Synopsis¶
display name: Workload Balance Migration Strategy
goal: workload_balancing
[PoC]Workload balance using live migration
Description
It is a migration strategy based on the VM workload of physical servers. It generates solutions to move a workload whenever a server’s CPU or RAM utilization % is higher than the specified threshold. The VM to be moved should make the host close to average workload of all compute nodes.Requirements
- Hardware: compute node should use the same physical CPUs/RAMs
- Software: Ceilometer component ceilometer-agent-compute running in each compute node, and Ceilometer API can report such telemetry “cpu_util” and “memory.resident” successfully.
- You must have at least 2 physical compute nodes to run this strategy.
Limitations
- This is a proof of concept that is not meant to be used in production
- We cannot forecast how many servers should be migrated. This is the reason why we only plan a single virtual machine migration at a time. So it’s better to use this algorithm with CONTINUOUS audits.
- It assume that live migrations are possible
Requirements¶
None.
Metrics¶
The workload_balance strategy requires the following metrics:
| metric | service name | plugins | comment |
|---|---|---|---|
cpu_util |
ceilometer | none | |
memory.resident |
ceilometer | 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 migrationMigrates 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.
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 |
|---|---|---|---|
metrics |
String | ‘cpu_util’ | Workload balance base on cpu or ram utilization. choice: [‘cpu_util’, ‘memory.resident’] |
threshold |
Number | 25.0 | Workload threshold for migration |
period |
Number | 300 | Aggregate time period of ceilometer |
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 ?¶
$ openstack optimize audittemplate create \
at1 workload_balancing --strategy workload_balance
$ openstack optimize audit create -a at1 -p threshold=26.0 \
-p period=310 -p metrics=cpu_util
External Links¶
None.
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