Comment 13 for bug 1560965

Can confirm that what you provided in #6 fixes the issue (with Mitaka, looks the same for Newton), and it makes complete sense to let the image metadata, or the hypervisor software (ie. xen/kvm) dictate what the primary disk is going to be labeled.

I also had the same issue, where we had set "disk_prefix = sd" in nova.conf, along with "hw_scsi_model=virtio-scsi" and "hw_disk_bus=scsi" on images (as we're using Ceph), however the the primary disk would appear as /dev/vda in Horzion, and /dev/sda in the VM.

Consequent disk's being added from there would appear as /dev/sd[b/d/c] in horizon, however they would not mount due to the device being in use and cause all sorts of issues from there (to the point that the VM will not boot if restarted).

After applying the patch (from #6), disks appear as expected in order (eg. /dev/sd[a/b/c]).