openstack
/
cinderlib
Code Issues Proposed changes

Improve stats documentation 

In the documentation we mention that collecting the stats is an
expensive operation and that we can read from the cache, but we don't
mention that reading from the cache is the default or how we can force a
refresh.

This patch modifies the backends topic in the documentation to include
this information.
This commit is contained in:
Gorka Eguileor 2018-03-14 18:38:51 +01:00
parent 80356715c3
commit 69e1b65c18
1 changed files with 6 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
docs/topics/backends.rst
View File

@ -152,15 +152,17 @@ Additional information can be found in the `Volume Stats section
<https://docs.openstack.org/cinder/pike/contributor/drivers.html#volume-stats>`_
within the Developer's Documentation.
Gathering stats is a costly operation for many storage backends, so we have the
possibility of retrieving the cached value that was retrieved the last time.
Gathering stats is a costly operation for many storage backends, so by default
the stats method will return cached values instead of collecting them again.
If latest data is required parameter `refresh=True` should be passed in the
`stats` method call.
Here's an example of the output from the LVM *Backend*:
Here's an example of the output from the LVM *Backend* with refresh:
.. code-block:: python
>>> from pprint import pprint
>>> pprint(lvm.stats())
>>> pprint(lvm.stats(refresh=True))
{'driver_version': '3.0.0',
'pools': [{'QoS_support': False,
'filter_function': None,