Ah thanks, you're right. Cinder will have the same issue you're describing, though. Didn't re-read the code fully yet, but I think that for cinder, this means we will need to change Disk.claim("foo") to return true if it's already claimed for foo. If that's true, we probably want to do the claim in disk_test_expr here too (and keep most of disk_enum_expr as it is).