Configure Live Migration Parameters in Nova¶
About this task
You can configure a maximum time for a live migration to complete and/or the maximum downtime target for live migration switchover.
Time to wait, in seconds, for live migration to successfully complete transferring data before aborting the operation.
Value is per GiB of guest RAM + disk to be transferred, with a lower boundary of 2 GiB. Set to 0 to disable timeouts.
The target maximum period of time that Nova will require the VM to be paused in order to complete the VM memory copy. If the transfer rate slows down after the VM has been paused, this value can be exceeded by a small amount of time, it will be rounded up to a minimum of 100ms.
You may increase this value if you want to allow live-migrations to complete faster, or avoid
live-migrationtimeout errors by allowing the guest to be paused longer during the
live_migration_downtime_scopeparameters can be modified:
Sets the total number of adjustment steps until
live_migration_downtimeis reached. This will let nova increase
live_migration_downtimegradually until either the switchover has been completed or the maximum value has been reached. The default is 10 steps.
Sets the time interval between two adjustment steps in seconds. The default is 75.
All the parameters can be modified using the Helm overrides for the StarlingX OpenStack application.
Create a yaml file containing the configuration update.
conf: nova: libvirt: live_migration_completion_timeout: 300 live_migration_downtime: 600 live_migration_downtime_steps: 12 live_migration_downtime_delay: 50
Update the Helm overrides using the new configuration file.
~(keystone_admin)]$ system helm-override-update --values ./nova_override.yaml wr-openstack nova openstack --reuse-values
Confirm that the user override lists the correct live migration parameters.
~(keystone_admin)]$ system helm-override-show wr-openstack nova openstack
Apply the changes.
~(keystone_admin)]$ system application-apply wr-openstack
If the live migration aborts because
been exceeded, then the following message appears on the
WARNING nova.virt.libvirt.migration [-] [instance: 07b5842b-6324-4de0-973e-6d0ff18ef574] Live migration not completed after 300 seconds
The default behavior is to abort the operation. You can change this action by
live_migration_timeout_action in your yaml file.
If it is set to
force_complete, the compute service will either pause the
VM or trigger post-copy if post copy is enabled and available
live_migration_permit_post_copy is set to True).