While mirroring /tumbleweed/repo/oss from another mirror via rsync it became clear that these secondary mirrors do not provide atomic updates. The files are updated in random order. Most likely rsync was invoked without --delay-updates. Perhaps also without --partial and proper --partial-dir=DIR, in case this actually combines well with --delay-updates, just to avoid errors like rsync: send_files failed to open "/tumbleweed/repo/oss/x86_64/.lazarus-2.0.12-2.1.x86_64.rpm.C11vZI" (in opensuse): Permission denied (13)
I do not know for how long rsync mirrors are offered. Was there any effort to provide mirror admins with instructions about how to mirror a volatile installation repo properly?
It is required to transfer repodata/repomd.xml at the very end to keep the repo itself consistent.
It is required to transfer /boot/x86_64 with --delay-updates to make sure the installer does not access incompatible files. This part might be tricky.
While I could certainly implement all the required checks myself to have a consistent local mirror, I wonder if this was already solved in a generic way, given the issue exists since a decade. smt-server and rmt-server deal with the repodata part already, but they miss support to mirror the inst-sys. And of course they are unable to fix a bad secondary mirror.