Please note: This schedule is for OpenStack Active Technical Contributors participating in the Icehouse Design Summit sessions in Hong Kong. These are working sessions to determine the roadmap of the Icehouse release and make decisions across the project. To see the full OpenStack Summit schedule, including presentations, panels and workshops, go to http://openstacksummitnovember2013.sched.org.
Currently the scheduler filters in Cinder works in strict manner, which means once a back-end failed to pass any one of the filters, this back-ends looses its chance of being chosen. It'd be useful if we can extend filter scheduler to support 'optional' or 'non-mandatory' filters. Back-ends are not immediately ruled out if they failed to pass optional/non-mandatory filters, instead, they will be considered as sub-optimal candidates and will only be chosen if no optimal back-ends can be found.
Meanwhile, the only weigher we have in Cinder is capacity weigher, which sorts back-ends by free space. This weigher is less useful than it sounds due to that fact that a lot of back-ends may report 'infinite' free space. So it's time to introduce new weighers that utilize more practical metrics as input, for example, allocated volumes, active volumes, active capacity. Since not all the metrics are available on all back-ends, a discussion is worthwhile to clarify the definitions and scope of these new metrics.
