Comment 20 for bug 1735839

From the field engineering perspective, 2 would suffice as it would preserve backwards compatibility and solve the problem for contemporary versions of MAAS.

I think (2) could be modified to instead avoid creating symlinks for devices that do not have persistent identifiers. Existing 2.2 to 2.4 installations would still be able to deploy virtual machines but dname symlinks would not be created. Pod VMs have 1 block device and dname symlinks are not generally used with them anyway.

This would provide a way to still provision virtual machines but avoid creating symlinks for devices without persistent ids (they must not be used anyway).

For physical block devices with valid VPD pages containing serial or wwid there would be no difference as symlinks were not available for them anyway unless a partition table was present.

(3) would require 2 SRUs (one for Xenial, one for Bionic) and also specific ordering of updates (MAAS first, then Curtin). This would set us back it terms of getting the newer Curtin version for a while I imagine.

Anything against the modified version of (2) I proposed?