Hi Matt, On 2015-09-24 1:45 PM, Matt Riedemann wrote: > > > On 9/24/2015 11:50 AM, Mathieu Gagné wrote: >> >> May I suggest the following solutions: >> >> 1) Add ability to disable this whole AZ concept in Cinder so it doesn't >> fail to create volumes when Nova asks for a specific AZ. This could >> result in the same behavior as cinder.cross_az_attach config. > > That's essentially what this does: > > https://review.openstack.org/#/c/217857/ > > It defaults to False though so you have to be aware and set it if you're > hitting this problem. > > The nova block_device code that tries to create the volume and passes > the nova AZ should have probably been taking into account the > cinder.cross_az_attach config option, because just blindly passing it > was the reason why cinder added that option. There is now a change up > for review to consider cinder.cross_az_attach in block_device: > > https://review.openstack.org/#/c/225119/ > > But that's still making the assumption that we should be passing the AZ > on the volume create request and will still fail if the AZ isn't in > cinder (and allow_availability_zone_fallback=False in cinder.conf). > > In talking with Duncan this morning he's going to propose a spec for an > attempt to clean some of this up and decouple nova from handling this > logic. Basically a new Cinder API where you give it an AZ and it tells > you if that's OK. We could then use this on the nova side before we > ever get to the compute node and fail.
IMO, the confusion comes from what I consider a wrong usage of AZ. To quote Sylvain Bauza from a recent review [1][2]: "because Nova AZs and Cinder AZs are very different failure domains" This is not the concept of AZ I learned to know from cloud providers where an AZ is global to the region, not per-service. Google Cloud Platform: - Persistent disks are per-zone resources. [3] - Resources that are specific to a zone or a region can only be used by other resources in the same zone or region. For example, disks and instances are both zonal resources. To attach a disk to an instance, both resources must be in the same zone. [4] Amazon Web Services: - Instances and disks are per-zone resources. [5] So now we are stuck with AZ not being consistent across services and confusing people. [1] https://review.openstack.org/#/c/225119/2 [2] https://review.openstack.org/#/c/225119/2/nova/virt/block_device.py [3] https://cloud.google.com/compute/docs/disks/persistent-disks [4] https://cloud.google.com/compute/docs/zones [5] http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/resources.html -- Mathieu __________________________________________________________________________ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
