ef769443fb
policy file default and JSON format 'policy.json' is now deprecated. Let's replace all the ref and test start using the policy.yaml. Change-Id: I78a273576702fb95d831bd9b801b5774fb9fd19e
112 lines
3.4 KiB
ReStructuredText
112 lines
3.4 KiB
ReStructuredText
=================
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Migrate instances
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=================
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.. note::
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This documentation is about cold migration. For live migration usage, see
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:doc:`live-migration-usage`.
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When you want to move an instance from one compute host to another, you can
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migrate the instance. The migration operation, which is also known as the cold
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migration operation to distinguish it from the live migration operation,
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functions similarly to :doc:`the resize operation </user/resize>` with the main
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difference being that a cold migration does not change the flavor of the
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instance. As with resize, the scheduler chooses the destination compute host
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based on its settings. This process does not assume that the instance has shared
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storage available on the target host. If you are using SSH tunneling, you must
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ensure that each node is configured with SSH key authentication so that the
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Compute service can use SSH to move disks to other nodes. For more information,
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see :ref:`cli-os-migrate-cfg-ssh`.
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To list the VMs you want to migrate, run:
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.. code-block:: console
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$ openstack server list
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Once you have the name or UUID of the server you wish to migrate, migrate it
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using the :command:`openstack server migrate` command:
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.. code-block:: console
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$ openstack server migrate SERVER
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Once an instance has successfully migrated, you can use the :command:`openstack
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server migrate confirm` command to confirm it:
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.. code-block:: console
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$ openstack server migrate confirm SERVER
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Alternatively, you can use the :command:`openstack server migrate revert`
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command to revert the migration and restore the instance to its previous host:
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.. code-block:: console
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$ openstack server migrate revert SERVER
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.. note::
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You can configure automatic confirmation of migrations and resizes. Refer to
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the :oslo.config:option:`resize_confirm_window` option for more information.
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Example
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-------
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To migrate an instance and watch the status, use this example script:
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.. code-block:: bash
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#!/bin/bash
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# Provide usage
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usage() {
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echo "Usage: $0 VM_ID"
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exit 1
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}
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[[ $# -eq 0 ]] && usage
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VM_ID=$1
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# Show the details for the VM
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echo "Instance details:"
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openstack server show ${VM_ID}
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# Migrate the VM to an alternate hypervisor
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echo -n "Migrating instance to alternate host "
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openstack server migrate ${VM_ID}
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while [[ "$(openstack server show ${VM_ID} -f value -c status)" != "VERIFY_RESIZE" ]]; do
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echo -n "."
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sleep 2
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done
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openstack server migrate confirm ${VM_ID}
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echo " instance migrated and resized."
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# Show the details for the migrated VM
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echo "Migrated instance details:"
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openstack server show ${VM_ID}
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# Pause to allow users to examine VM details
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read -p "Pausing, press <enter> to exit."
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.. note::
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If you see the following error, it means you are either running the command
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with the wrong credentials, such as a non-admin user, or the ``policy.yaml``
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file prevents migration for your user::
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Policy doesn't allow os_compute_api:os-migrate-server:migrate to be performed. (HTTP 403)
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.. note::
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If you see the following error, similar to this message, SSH tunneling was
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not set up between the compute nodes::
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ProcessExecutionError: Unexpected error while running command.
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Stderr: u Host key verification failed.\r\n
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The instance is booted from a new host, but preserves its configuration
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including instance ID, name, IP address, any metadata, and other properties.
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