Comment 1 for bug 2032916

I went on an archeological dig and assuming I didn't miss something: the short answer is that disk.local is an old/original representation of an ephemeral disk defined in the flavor and is no longer used.

There are two ways to specify ephemeral disk: in the flavor or in the block device mapping(s) in the server create request. The disk.local was for the former, when ephemeral disk was specified in the flavor and not in block device mapping(s). And originally ephemeral and swap disks from the flavor did not have block device mappings created for them.

Then there was a change a long time ago:

https://review.opendev.org/c/openstack/nova/+/83516

which changed things to create block device mappings for ephemeral and swap disks specified in the flavor, probably to move toward treating all cases in a more consistent manner.

After this, AFAICT any specified ephemeral disk would end up being considered as specified from block device mappings, so the code to create disk.local isn't reached anymore. There are always BDMs for ephemeral and swap, whether they're in the flavor or not.

I think you are right that there isn't a functionality bug here. To me it seems at worst what we have is some unused code, which doesn't hurt anything aside from being tech debt. And removing the code will take some care to make sure nothing else gets broken in the process.

Based on this, I'm marking this as Confirmed with Low priority.