VMware live migration

https://blueprints.launchpad.net/nova/+spec/vmware-live-migration

This is a proposal for adding support for live migration in the VMware driver. When the VMware driver is used, each nova-compute is managing a single vCenter cluster. For the purposes of this proposal we assume that all nova-computes are managing clusters under the same vCenter server. If migration across different vCenter servers is attempted, an error message will be generated and no migration will occur.

Problem description

Live migration is not supported when the VMware driver is used.

Use Cases

As an Operator I want to live migrate instances from one compute cluster (nova-compute host) to another compute cluster (nova-compute host) in the same vCenter server.

Proposed change

Relocating VMs to another cluster/datastore is a simple matter of calling the RelocateVM_Task() vSphere API. The source compute host needs to know the cluster name and the datastore regex of the target compute host. If the instance is located on a datastore shared between the two clusters, it will remain there. Otherwise we will choose a datastore that matches the datastore_regex of the target host and migrate the instance there. There will be a pre live-migration check that will verify that both source and destination compute nodes correspond to clusters in the same vCenter server.

A new object will be introduced (VMwareLiveMigrateData) which will carry the host IP, the cluster name and the datastore regex of the target compute host. All of them are obtained from the nova config (CONF.vmware.host_ip, CONF.vmware.cluster_name and CONF.vmware.datastore_regex).

Alternatives

None

Data model impact

None

REST API impact

None

Security impact

None

Notifications impact

None

Other end user impact

None

Performance Impact

None

Other deployer impact

None

Developer impact

None

Upgrade impact

None

Implementation

https://review.openstack.org/#/c/270116/

Assignee(s)

Primary assignee:

rgerganov

Work Items

  • Add VMwareLiveMigrateData object

  • Implement pre live-migration checks

  • Implement methods for selecting target ESX host and datastore

  • Ensure CI coverage for live-migration

  • Update support-matrix

Dependencies

None

Testing

The VMware CI will provision two nova-computes and will execute the live migration tests from tempest.

Documentation Impact

The feature support matrix should be updated to indicate that live migration is supported with the VMware driver.

History

Revisions

Release Name

Description

Newton

Introduced

Ocata

Reproposed

Pike

Reproposed

Queens

Reproposed

Rocky

Reproposed