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Created section about Live Migration in Nova (pick r6)

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New section added to explain how to change live_migration_completion_timeout parameter and replacing Configure a Live Migration Completion Timeout in Nova
Fixed typo.

Signed-off-by: Elisamara Aoki Goncalves <elisamaraaoki.goncalves@windriver.com>
Change-Id: If025df41ea6a5e28a258a966f74249b116c26633
This commit is contained in:
Elisamara Aoki Goncalves 2022-03-25 11:08:52 -03:00
parent 465c851c17
commit 5c8876e763
3 changed files with 109 additions and 58 deletions
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108
doc/source/system_configuration/openstack/configure-a-live-migration-parameters-in-nova-6154238dfc6d.rst Normal file
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.. _configure-a-live-migration-parameters-in-nova-6154238dfc6d:
===========================================
Configure Live Migration Parameters in Nova
===========================================
.. rubric:: |context|
You can configure a maximum time for a live migration to complete and/or the
maximum downtime target for live migration switchover.
----------
Parameters
----------
- ``live_migration_completion_timeout``
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.
- ``live_migration_downtime``
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-migration`` timeout errors by allowing the
guest to be paused longer during the ``live-migration`` switch over.
Two additional ``live_migration_downtime_scope`` parameters can be
modified:
- ``live_migration_downtime_steps``
Sets the total number of adjustment steps until
``live_migration_downtime`` is reached. This will let nova increase
``live_migration_downtime`` gradually until either the switchover has
been completed or the maximum value has been reached. The default is 10
steps.
- ``live_migration_downtime_delay``
Sets the time interval between two adjustment steps in seconds. The
default is 75.
.. rubric:: |proc|
All the parameters can be modified using the Helm overrides for the |prod-os|
application.
#. Create a yaml file containing the configuration update.
For example ``nova_override.yaml``:
.. code-block:: none
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.
.. code-block:: none
~(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.
.. code-block:: none
~(keystone_admin)]$ system helm-override-show wr-openstack nova openstack
#. Apply the changes.
.. code-block:: none
~(keystone_admin)]$ system application-apply wr-openstack
.. rubric:: |result|
If the live migration aborts because ``live_migration_completion_timeout`` has
been exceeded, then the following message appears on the ``nova_compute`` logs:
.. code-block:: none
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
configuring ``live_migration_timeout_action`` in your yaml file.
For example:
.. code-block:: none
live_migration_timeout_action: force_complete
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).

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doc/source/system_configuration/openstack/configuring-a-live-migration-completion-timeout-in-nova.rst
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.. err1590511228224
.. _configuring-a-live-migration-completion-timeout-in-nova:
=====================================================
Configure a Live Migration Completion Timeout in Nova
=====================================================
You can configure how long to allow for a compute live migration to
complete before the operation is aborted.
.. rubric:: |context|
The following example applies a timeout of 300 seconds to all hosts.
The same basic workflow of *creating an overrides file*, then
*using it to update helm overrides for the application*, and finally
*reapplying the application to make your changes effective* can be used
to apply other Nova overrides globally.
.. rubric:: |proc|
#. Create a yaml configuration file containing the configuration update.
.. code-block:: none
~(keystone_admin)]$ cat << EOF > ./nova_override.yaml
conf:
nova:
libvirt:
live_migration_completion_timeout: 300
EOF
#. Update the Helm overrides using the new configuration file.
.. parsed-literal::
~(keystone_admin)]$ system helm-override-update --reuse-values --values ./nova_override.yaml |prefix|-openstack nova openstack --reuse-values
#. Confirm that the user\_override lists the correct live migration completion timeout.
.. parsed-literal::
~(keystone_admin)$ system helm-override-show |prefix|-openstack nova openstack
The output should include the following:
.. code-block:: none
live_migration_completion_timeout: 300
#. Apply the changes.
.. parsed-literal::
~(keystone_admin)]$ system application-apply |prefix|-openstack

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doc/source/system_configuration/openstack/index-sysconf-os-988a21c687cb.rst
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@ -16,7 +16,7 @@ Configure OpenStack Services Using Helm Chart Overrides
:maxdepth: 1
system-configuration-overview
configuring-a-live-migration-completion-timeout-in-nova
configure-a-live-migration-parameters-in-nova-6154238dfc6d
configuring-a-pci-alias-in-nova
configuring-the-rpc-response-timeout-in-cinder
configure-the-nfs-backend-on-cinder-backup