76 lines
2.5 KiB
ReStructuredText
76 lines
2.5 KiB
ReStructuredText
==================
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Reboot an instance
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==================
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You can soft or hard reboot a running instance. A soft reboot attempts a
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graceful shut down and restart of the instance. A hard reboot power
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cycles the instance.
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By default, when you reboot an instance, it is a soft reboot.
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.. code-block:: console
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$ openstack server reboot SERVER
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To perform a hard reboot, pass the :option:`--hard` parameter, as follows:
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.. code-block:: console
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$ openstack server reboot --hard SERVER
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It is also possible to reboot a running instance into rescue mode. For example,
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this operation may be required, if a filesystem of an instance becomes
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corrupted with prolonged use.
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.. note::
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Pause, suspend, and stop operations are not allowed when an instance
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is running in rescue mode, as triggering these actions causes the
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loss of the original instance state, and makes it impossible to
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unrescue the instance.
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Rescue mode provides a mechanism for access, even if an image renders
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the instance inaccessible. By default, it starts an instance from the
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initial image attaching the current boot disk as a secondary one.
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To perform an instance reboot into rescue mode, run the following
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command:
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.. code-block:: console
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$ openstack server rescue SERVER
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.. note::
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On running the :command:`nova rescue` command,
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an instance performs a soft shutdown first. This means that
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the guest operating system has a chance to perform
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a controlled shutdown before the instance is powered off.
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The shutdown behavior is configured by the ``shutdown_timeout``
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parameter that can be set in the ``nova.conf`` file.
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Its value stands for the overall period (in seconds)
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a guest operation system is allowed to complete the shutdown.
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The default timeout is 60 seconds. See `Description of
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Compute configuration options
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<http://docs.openstack.org/newton/config-reference/compute/config-options.html>`_
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for details.
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The timeout value can be overridden on a per image basis
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by means of ``os_shutdown_timeout`` that is an image metadata
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setting allowing different types of operating systems to specify
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how much time they need to shut down cleanly.
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To restart the instance from the normal boot disk, run the following
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command:
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.. code-block:: console
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$ openstack server unrescue SERVER
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If you want to rescue an instance with a specific image, rather than the
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default one, use the :option:`--rescue_image_ref` parameter:
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.. code-block:: console
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$ nova rescue --rescue_image_ref IMAGE_ID SERVER
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