openstack/cinder
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Merge "Improve documentation of goodness/filter function"

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Zuul 2019-03-05 23:57:39 +00:00 committed by Gerrit Code Review
commit 5c7424c828
1 changed files with 26 additions and 11 deletions
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37
doc/source/admin/blockstorage-driver-filter-weighing.rst
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@ -32,8 +32,9 @@ Enable driver filter and weighing
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
To enable the driver filter, set the ``scheduler_default_filters`` option in
the ``cinder.conf`` file to ``DriverFilter`` or add it to the list if
other filters are already present.
the ``cinder.conf`` file to ``DriverFilter``. The DriverFilter can also be
used along with other filters by adding it to the list if other filters are
already present.
To enable the goodness filter as a weigher, set the
``scheduler_default_weighers`` option in the ``cinder.conf`` file to
@ -47,10 +48,8 @@ choose an ideal back end.
.. important::
The support for the ``DriverFilter`` and ``GoodnessWeigher`` is
optional for back ends. If you are using a back end that does not
support the filter and weigher functionality you may not get the
full benefit.
The GoodnessWeigher can be used along with CapacityWeigher and others,
but must be used with caution as it might obfuscate the CapacityWeigher.
Example ``cinder.conf`` configuration file:
@ -64,7 +63,8 @@ Example ``cinder.conf`` configuration file:
It is useful to use the other filters and weighers available in
OpenStack in combination with these custom ones. For example, the
``CapacityFilter`` and ``CapacityWeigher`` can be combined with
these.
these. Using them together should be done with caution as depending
on the defined logic, one might obfuscate the other.
Defining your own filter and goodness functions
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@ -132,6 +132,10 @@ available for use:
Host stats for a back end
-------------------------
In order to access these properties, use the following format:
``stats.<property>``
host
The host's name
@ -156,6 +160,9 @@ total\_capacity\_gb
allocated\_capacity\_gb
The allocated capacity in GB
free\_capacity\_gb
The free capacity in GB
reserved\_percentage
The reserved storage percentage
@ -164,11 +171,19 @@ Capabilities specific to a back end
These properties are determined by the specific back end
you are creating filter and goodness functions for. Some back ends
may not have any properties available here.
may not have any properties available here. Once the capabilities vary
too much according to the backend, it is better to check its properties
reported on the scheduler log. The scheduler reports these capabilities
constantly.
In order to access these properties, use the following format:
``capabilities.<property>``
Requested volume properties
---------------------------
In order to access the volume properties, use the following format:
``volume.<property>``
status
Status for the requested volume
@ -366,8 +381,8 @@ The above is an example of how back-end specific properties can be used
in the filter and goodness functions. In this example the LVM driver's
``total_volumes`` capability is being used to determine which host gets
used during a volume request. In the above example, lvm-1 and lvm-2 will
handle volume requests for all volumes with a size less than 5 GB. The
lvm-1 host will have priority until it contains three or more volumes.
After than lvm-2 will have priority until it contains eight or more
handle volume requests for all volumes with a size less than 5 GB. Both
lvm-1 and lvm-2 will have the same priority while lvm-1 contains 3 or less
volumes. After that lvm-2 will have priority while it contains 8 or less
volumes. The lvm-3 will collect all volumes greater or equal to 5 GB as
well as all volumes once lvm-1 and lvm-2 lose priority.