OpenStack Kilo Design Summit

Led by: Xing Yang & Eoghan Glynn
'infinite' and 'unknown' were initially used for capacity reporting for vendors using thin provisioning. They are now given the lowest weighing and are not the recommended way of reporting capacities. The proposal is to include virtual capacity in capacity reporting and allow over subscription for thin provisioning. Virtual capacity "provisioned_capacity_gb" was already part of Winston's spec https://review.openstack.org/#/c/105190/6/specs/juno/volume-statistics-reporting.rst. This proposal adds support for "over subscription" in thin provisioning and will be built on top of Winston's spec.


* Backend reports virtual capacity in get_volume_stats, in addition to total capacity and free capacity.
* Scheduler checks available virtual capacity and available real capacity.
* Over subscription ratio will be used to control virtual capacity allocation.
* Used ratio will be used to control real capacity usage.
*These two ratios should prevent over provisioning.
* Send notification if capacity reaches upper limit controlled by over subscription ratio or used ratio.
* cinder spec: https://review.openstack.org/#/c/129342/