openstack/nova
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docs: Extract rescue from reboot

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This change simply extracts and slightly reorders the existing rescue
documentation from the reboot reference page.

Closes-Bug: #1852609
Change-Id: I4ce8874aa3e879e89ab5c7c76162561acbdea5c4
This commit is contained in:
Lee Yarwood 2019-11-15 11:59:26 +00:00 committed by Matt Riedemann
parent 4e6d5ee81b
commit 7f46b9b281
3 changed files with 55 additions and 51 deletions
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1
doc/source/user/index.rst
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@ -15,6 +15,7 @@ End user guide
certificate-validation
resize
reboot
rescue
availability-zones
block-device-mapping
/reference/api-microversion-history

53
doc/source/user/reboot.rst
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@ -20,54 +20,5 @@ To perform a hard reboot, pass the ``--hard`` parameter as follows:
$ openstack server reboot --hard SERVER
It is also possible to reboot a running instance into rescue mode. For example,
this operation may be required if a filesystem of an instance becomes
corrupted with prolonged use.
.. note::
Pause, suspend, and stop operations are not allowed when an instance
is running in rescue mode, as triggering these actions causes the
loss of the original instance state and makes it impossible to
unrescue the instance.
Rescue mode provides a mechanism for access, even if an image renders
the instance inaccessible. By default, it starts an instance from the
initial image attaching the current boot disk as a secondary one.
To perform an instance reboot into rescue mode, use the :command:`openstack
server rescue` command:
.. code-block:: console
$ openstack server rescue SERVER
.. note::
On running the :command:`openstack server rescue` command,
an instance performs a soft shutdown first. This means that
the guest operating system has a chance to perform
a controlled shutdown before the instance is powered off.
The shutdown behavior is configured by the
:oslo.config:option:`shutdown_timeout` parameter that can be set in the
``nova.conf`` file.
Its value stands for the overall period (in seconds)
a guest operating system is allowed to complete the shutdown.
The timeout value can be overridden on a per image basis
by means of ``os_shutdown_timeout`` that is an image metadata
setting allowing different types of operating systems to specify
how much time they need to shut down cleanly.
To restart the instance from the normal boot disk, run the following
command:
.. code-block:: console
$ openstack server unrescue SERVER
If you want to rescue an instance with a specific image, rather than the
default one, use the ``--image`` parameter:
.. code-block:: console
$ openstack server rescue --image IMAGE_ID SERVER
this operation may be required if a filesystem of an instance becomes corrupted
with prolonged use. See :doc:`rescue` for more details.

52
doc/source/user/rescue.rst Normal file
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@ -0,0 +1,52 @@
==================
Rescue an instance
==================
Rescue mode provides a mechanism for access, even if an image renders
the instance inaccessible. By default, it starts an instance from the
initial image attaching the current boot disk as a secondary one.
.. note::
Pause, suspend, and stop operations are not allowed when an instance
is running in rescue mode, as triggering these actions causes the
loss of the original instance state and makes it impossible to
unrescue the instance.
To perform an instance rescue, use the :command:`openstack server rescue`
command:
.. code-block:: console
$ openstack server rescue SERVER
.. note::
On running the :command:`openstack server rescue` command,
an instance performs a soft shutdown first. This means that
the guest operating system has a chance to perform
a controlled shutdown before the instance is powered off.
The shutdown behavior is configured by the
:oslo.config:option:`shutdown_timeout` parameter that can be set in the
``nova.conf`` file.
Its value stands for the overall period (in seconds)
a guest operating system is allowed to complete the shutdown.
The timeout value can be overridden on a per image basis
by means of ``os_shutdown_timeout`` that is an image metadata
setting allowing different types of operating systems to specify
how much time they need to shut down cleanly.
If you want to rescue an instance with a specific image, rather than the
default one, use the ``--image`` parameter:
.. code-block:: console
$ openstack server rescue --image IMAGE_ID SERVER
To restart the instance from the normal boot disk, run the following
command:
.. code-block:: console
$ openstack server unrescue SERVER