openstack/ironic
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[doc] Update documentation about force_persistent_boot_device

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Apparently, this was missed when the new options were introduced.

Story: #2004846

Change-Id: I04be5a5a8fa962bafa68f0ea93ee127b1610c20f
This commit is contained in:
Arne Wiebalck 2021-05-10 19:00:22 +02:00
parent 541de6036c
commit 754f15c92d
1 changed files with 19 additions and 9 deletions
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28
doc/source/admin/interfaces/boot.rst
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@ -45,21 +45,31 @@ Common options
Enable persistent boot device for deploy/clean operation
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Ironic uses non-persistent boot for cleaning/deploying phases as default.
For some drivers, a persistent change is far more costly than a non-persistent
one, so this can bring performance improvements.
For (i)PXE booting, Ironic uses non-persistent boot order changes for
clean/deploy by default. For some drivers, persistent changes are far
more costly than non-persisent ones, so this approach can bring a
performance benefit.
Set the flag ``force_persistent_boot_device`` to ``True`` in the node's
``driver_info``::
In order to control this behavior, however, Ironic provides the
``force_persistent_boot_device`` flag in the node's ``driver_info``.
It allows the values ``Default`` (make all changes but the last one
upon deployment non-persistent), ``Always`` (make all changes persistent),
and ``Never`` (make all boot order changes non-persistent). For example
in order to have only persistent changes one would need to set something
like::
$ baremetal node set --driver-info force_persistent_boot_device=True <node>
$ openstack baremetal node set --driver-info force_persistent_boot_device='Always' <node>
.. note::
It's recommended to check if the node's state has not changed as there
It is recommended to check if the node's state has not changed as there
is no way of locking the node between these commands.
Once the flag is present, the next cleaning and deploy steps will be done
with persistent boot for that node.
.. note::
The values 'True'/'False' for the option 'force_persistent_boot_device'
in the node's driver info for the (i)PXE drivers are deprecated and
support for them may be removed in a future release. The former default
value 'False' is replaced by the new value 'Default', the value 'True'
is replaced by 'Always'.
.. _PXE: https://en.wikipedia.org/wiki/Preboot_Execution_Environment