[openstack-dev] [cinder][ceilometer] cinder capacity notifications

Gorka Eguileor geguileo at redhat.com
Tue Dec 19 11:57:12 UTC 2017

On 12/12, gordon chung wrote:
> hi,
> i'm attempting to add support for the cinder capacity notifications that
> were added a while back[1].
> adding measurement support in ceilometer is pretty simple where in most
> cases you just add an entry to a yaml file[2]. the problem i have right
> now is i have no idea what resource these measurement are measuring so
> i'm unsure how to name the measurement in ceilometer so a user can
> understand what it's measuring.
> the following are probably stupid questions but i see it measures two
> different resource types, a 'pool' and a 'backend' and they are
> ultimately tied to a host. are these measuring the amount of disk on
> each host? our pools confined to a host?
> anyone with better knowledge is welcomed to take over my patch.
> [1] https://review.openstack.org/#/c/206923
> [2] https://review.openstack.org/#/c/526538
> cheers,
> --
> gord
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Here's a brief explanation of the 3 names you mention:

- host: A node were cinder-volume service is running
- backend: A set of driver configurations used to access a specific
  storage.  A cinder-volume service can have multiple backends.
- pool: A logical concept to describe a set of storage resource that can
  be used to serve core Cinder requests.  A backend can have multiple
  pools, each with different characteristics.

Cinder-volume services are named taking these 3 names and joining them
like: host at backend#pool

As for the data that is being reported, this is mostly explained in the
latest spec [1], except the virtual_free which is basically the
available space taking into account the over provisioning.

More information on the pools can be found in the Juno specs [2].

I hope this helps.


[1] https://specs.openstack.org/openstack/cinder-specs/specs/queens/provisioning-improvements.html
[2] https://specs.openstack.org/openstack/cinder-specs/specs/juno/pool-aware-cinder-scheduler.html

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