[ironic][glance] tradeoffs between ceph and swift glance backends for ironic+kvm?

Hey!

We’re looking into deploying a cloud with a mix of VM and baremetal hosts (nova-compute vs ironic), and discovered some tension between the recommendations for glance for each case. At scale, ironic seems to recommend usage of the swift backend to remove the conductor as a bottleneck when streaming disk images, but for KVM usage, the RBD backend allows for faster launches by cloning the source image.

Any thoughts on these or any other tradeoffs, or some recommended configurations?

Thanks! -Mike

-- Michael Sherman Infrastructure Lead – Chameleon Computer Science, University of Chicago MCS, Argonne National Lab