openstack/nova
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docs: Document how to revert, confirm a cold migration

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This relies on the recently added 'openstack server migrate confirm' and
'openstack server migrate revert' commands.

Change-Id: I58d0a62aeeb4bb23a7ed3a8e9fe5ddb7f2dd3877
Signed-off-by: Stephen Finucane <sfinucan@redhat.com>
Depends-On: I0cb6304c794bffaec785add9f7b8cf53ab28cacd
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Stephen Finucane 2019-06-10 17:42:37 +01:00 committed by Stephen Finucane
parent 627c461a62
commit 775d89ed0f
1 changed files with 69 additions and 41 deletions
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doc/source/admin/migration.rst
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@ -4,64 +4,92 @@ Migrate instances
.. note::
This documentation is about cold-migration. For live-migration usage, see
This documentation is about cold migration. For live migration usage, see
:doc:`live-migration-usage`.
When you want to move an instance from one compute host to another, you can use
the :command:`openstack server migrate` command. The scheduler chooses the
destination compute host based on its settings. This process does not assume
that the instance has shared storage available on the target host. If you are
using SSH tunneling, you must ensure that each node is configured with SSH key
authentication so that the Compute service can use SSH to move disks to other
nodes. For more information, see :ref:`cli-os-migrate-cfg-ssh`.
When you want to move an instance from one compute host to another, you can
migrate the instance. The migration operation, which is also known as the cold
migration operation to distinguish it from the live migration operation,
functions similarly to :doc:`the resize operation </user/resize>` with the main
difference being that a cold migration does not change the flavor of the
instance. As with resize, the scheduler chooses the destination compute host
based on its settings. This process does not assume that the instance has shared
storage available on the target host. If you are using SSH tunneling, you must
ensure that each node is configured with SSH key authentication so that the
Compute service can use SSH to move disks to other nodes. For more information,
see :ref:`cli-os-migrate-cfg-ssh`.
#. To list the VMs you want to migrate, run:
To list the VMs you want to migrate, run:
.. code-block:: console
.. code-block:: console
$ openstack server list
$ openstack server list
#. Use the :command:`openstack server migrate` command.
Once you have the name or UUID of the server you wish to migrate, migrate it
using the :command:`openstack server migrate` command:
.. code-block:: console
.. code-block:: console
$ openstack server migrate VM_INSTANCE
$ openstack server migrate SERVER
#. To migrate an instance and watch the status, use this example script:
Once an instance has successfully migrated, you can use the :command:`openstack
server migrate confirm` command to confirm it:
.. code-block:: bash
.. code-block:: console
#!/bin/bash
$ openstack server migrate confirm SERVER
# Provide usage
usage() {
echo "Usage: $0 VM_ID"
exit 1
}
Alternatively, you can use the :command:`openstack server migrate revert`
command to revert the migration and restore the instance to its previous host:
[[ $# -eq 0 ]] && usage
VM_ID=$1
.. code-block:: console
# Show the details for the VM
echo "Instance details:"
openstack server show ${VM_ID}
$ openstack server migrate revert SERVER
# Migrate the VM to an alternate hypervisor
echo -n "Migrating instance to alternate host "
openstack server migrate ${VM_ID}
while [[ "$(openstack server show ${VM_ID} -f value -c status)" != "VERIFY_RESIZE" ]]; do
echo -n "."
sleep 2
done
openstack server resize --confirm ${VM_ID}
echo " instance migrated and resized."
.. note::
# Show the details for the migrated VM
echo "Migrated instance details:"
openstack server show ${VM_ID}
You can configure automatic confirmation of migrations and resizes. Refer to
the :oslo.config:option:`resize_confirm_window` option for more information.
# Pause to allow users to examine VM details
read -p "Pausing, press <enter> to exit."
Example
-------
To migrate an instance and watch the status, use this example script:
.. code-block:: bash
#!/bin/bash
# Provide usage
usage() {
echo "Usage: $0 VM_ID"
exit 1
}
[[ $# -eq 0 ]] && usage
VM_ID=$1
# Show the details for the VM
echo "Instance details:"
openstack server show ${VM_ID}
# Migrate the VM to an alternate hypervisor
echo -n "Migrating instance to alternate host "
openstack server migrate ${VM_ID}
while [[ "$(openstack server show ${VM_ID} -f value -c status)" != "VERIFY_RESIZE" ]]; do
echo -n "."
sleep 2
done
openstack server migrate confirm ${VM_ID}
echo " instance migrated and resized."
# Show the details for the migrated VM
echo "Migrated instance details:"
openstack server show ${VM_ID}
# Pause to allow users to examine VM details
read -p "Pausing, press <enter> to exit."
.. note::