In every case when Glance use RBD and client upload image from non-RBD source Glance will use resize-before-write.
When you need to upload large images or create large instance snapshots from non-RBD ephemeral storages it becomes a real problem.
As Stuart suggested in comment to the patch set, maybe optional size field should be added to the json during initial create image POST request?
Another possibility I can think of is to reuse min_disk field, since RBD stores image in raw anyway.
Would be happy to assist anyone interested in fixing this bug, but can't handle it alone.
The issue is the same as https:/ /bugs.launchpad .net/glance/ +bug/1792710.
In every case when Glance use RBD and client upload image from non-RBD source Glance will use resize- before- write.
When you need to upload large images or create large instance snapshots from non-RBD ephemeral storages it becomes a real problem.
As Stuart suggested in comment to the patch set, maybe optional size field should be added to the json during initial create image POST request?
Another possibility I can think of is to reuse min_disk field, since RBD stores image in raw anyway.
Would be happy to assist anyone interested in fixing this bug, but can't handle it alone.