[Bug 1893775] Re: [UBUNTU 20.04.1] Failure to install Ubuntu 20.04.1 as KVM guest on DASD

[Frank Heimes]

Since there are some discussions about this ticket on other
communication channels, I want to clarify and sum up the situation here:

An installation on a DASD disk that is virtio-attached, like:
virt-install --name focal --memory 2048 --disk path=/dev/disk/by-path/ccw-0.0.1234 --cdrom ./install_image.iso
works with d-i since, there is a 'non-standard way' (or one may call it 'hack') to identify that a certain disk that is passed over via virtio is not (as usual) a SCSI disk, but a DASD (based on the partition table).
We think that the clean way is to pass/attach DASD disks as ccw devices (what they actually are),
but we will look into this, since it worked with d-i.
Since this is a non-straight forward way to identify disk geometry, something like this would require 'extra coding' (or again some hacking).

However, nobody should be blocked by this, since there is still the focal / 20.04 legacy d-i image available, that allows such virt-install installation, like (in short):
virt-install --name focal --memory 2048 --disk path=/dev/disk/by-path/ccw-0.0.261e --cdrom ./ubuntu-20.04-legacy-server-s390x.iso
(for details see the attachment)

Even if the legacy d-i image is based on 20.04 GA, an installation (with
access to the archives) will end up as a proper 20.04.1 installation (as
of today), since the installer updates by default to the latest package
levels.

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Title:
  [UBUNTU 20.04.1] Failure to install Ubuntu 20.04.1 as KVM guest on
  DASD

Status in Ubuntu on IBM z Systems:
  Triaged
Status in subiquity package in Ubuntu:
  Incomplete
Status in subiquity source package in Focal:
  Incomplete
Status in subiquity source package in Groovy:
  Incomplete

Bug description:
  ---Problem Description---
  Failure to install Ubuntu 20.04.1 as KVM guest on DASD
    
  ---uname output---
  Linux version 5.4.0-42-generic (buildd at bos02-s390x-003) (gcc version 9.3.0 (Ubuntu 9.3.0-10ubuntu2)) #46-Ubuntu SMP Fri Jul 10 00:21:32 UTC 2020 (Ubuntu 5.4.0-42.46-generic 5.4.44)
   
  Machine Type = 3096-703 
   
  ---boot type---
  CDROM / ISO image
   
  ---Install repository type---
  Internet repository
   
  ---Install repository Location---
  ports.ubunut.com
   
  ---Point of failure---
  Other failure during installation (stage 1)

  I tried to install an Ubuntu 20.04.1 guest from ISO which failed.
  Steps to reproduce.
  1. Boot from ISO to start installer, in my case I used virt-install, but a manually defined libvirt domain has the same issue:
  $ virt-install --name focal.1 --memory 2048 --disk path=/dev/disk/by-path/ccw-0.0.a03f --cdrom ubuntu-20.04.1-live-server-s390x.iso

  2. On the installer screen, stay in simple mode and accept all
  defaults

  3. Shortly after a error pop-up appears, saying the installation has failed. Opening the log I see:
  ...
   storage:
     config:
     - {ptable: gpt, path: /dev/vda, wipe: superblock-recursive, preserve: false, name: '',
       grub_device: false, type: disk, id: disk-vda}
     - {device: disk-vda, size: 22153265152, wipe: superblock, flag: '', number: 1, preserve: false,
       type: partition, id: partition-0}
     - {fstype: ext4, volume: partition-0, preserve: false, type: format, id: format-0}
     - {device: format-0, path: /, type: mount, id: mount-0}
     version: 1
  ...
  An error occured handling 'format-0': OSError - could not get path to dev from kname: vda1
   finish: cmd-install/stage-partitioning/builtin/cmd-block-meta: FAIL: configuring format: format-0
   TIMED BLOCK_META: 1.942
   finish: cmd-install/stage-partitioning/builtin/cmd-block-meta: FAIL: curtin command block-meta

  
  It seems that the new installation procedure isn't correctly detecting virtio-attached DASDs and tries to handle them like SCSI disks (gpt label, ...). This is a regression compared to the debian-installer and prevents the installation of Ubuntu 20.04 KVM guests on DASD.

  I cross-checked by running the installation on a QCOW2 image, which
  succeeded without problems.

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