subiquity installer does not allow to delete existing partition

[Frank Heimes]

While doing a subiquity installation on s390x using DASD disk storage that was used before and was therefore already partitioned, I wanted to change the partition layout during install time.
But in the 'Storage configuration' task I was not able to delete an existing partition:

   ┌───────────────── Cannot delete partition of local disk ────────────────┐
   │ │
   │ Cannot delete a single partition from a device that already has │
   │ partitions. │
   │ │
   │ [ Close ] │
   │ │
   └────────────────────────────────────────────────────────────────────────┘

It should always be possible to delete an existing partition or to white out (low-level format in case of a DASD) the entire disk.
Otherwise existing and already used disks cannot be used with a different partition scheme anymore (without manual intervention).

subiquity 20.03.1 was in use.

Btw. I updated to 20.03.2, but subiquity didn't automatically restarted, and since I forgot to restart it manually I stayed on 20.03.1.

Not sure if this issue is the same for all disks, or limited to s390x DASD disks.

[Michael Hudson-Doyle (mwhudson)]

It's true that deleting an existing partition does not work. You should be able to reformat the whole disk, though?

[Frank Heimes (fheimes)]

Yes, that's correct.
Selecting the Format (Re-format) option on the entire disk itself will clean up the entire disk with all it's options and one can procced:

================================================================================
  Storage configuration [ Help ]
================================================================================
  To continue you need to: Mount a filesystem at /

  FILE SYSTEM SUMMARY ^
                                                                             │
    MOUNT POINT SIZE TYPE DEVICE TYPE │
  [ /boot 896.000M new ext4 new partition of local disk > ] │
                                                                             │
                                                                             │
  AVAILABLE DEVICES │
                                                                             │
    DEVICE TY┌─────────────────────────┐
  [ LX0200 lo│< (close) │
    free space │ Info >│
                                                     │ Reformat >│
  [ Create software RAID (md) > ] │ Add VTOC Partition >│
  [ Create volume group (LVM) > ] │ Format >│
                                                     │ Remove from RAID/LVM │
                                 [ Done ] └─────────────────────────┘
                                 [ Reset ]
                                 [ Back ]

The option to selectively delete a partition is just there (ready to use and not grayed out), hence I tried it. So of course nothing super critical ...

[Frank Heimes (fheimes)]

Yes, selecting the whole disk and formatting it entirely works.
(Just not selectively deleting a partition, like the menu let's one think ...)

[Frank Heimes (fheimes)]

I get from time to time feedback that the deletion of partitions is broken in subiquity and that people don't know what to do - they tend to go to the installer shell and do things manually ...

And I have to explain more often the workaround to Reformat and add VTOC-Partitions instead.
Would probably be worth to think about adding support to delete partitions selectively ...

[Brian Candler (b-candler)]

I have the same issue with subiquity in Ubuntu Server 22.04.3

I'd be quite happy to erase and recreate the entire partition table: subiquity offers this as "Reformat".

However if I do that, there is no option to create a vfat partition for /boot/efi. The only options it offers me are: ext4 | xfs | btrfs | swap | Leave unformatted

(and if I choose "Leave unformatted" then it greys out the mount point)

At this point, it looks like I'll have to drop out of the installer, delete the existing Windows partitions (leaving the EFI one alone), and then start the Ubuntu installer again from scratch.

It's not a great user experience, especially since this used to work fine in older versions of Ubuntu.

[Brian Candler (b-candler)]

(Aside: I had selected "update to the latest installer" during installation)

After going to Alt-F2, running parted with "rm 4", "rm 3", "rm 2", "quit", back to Alt-F1 and then selecting "Reset" in Subiquity, this was *almost* enough for it to pick up the updated partition table. It didn't show the deleted partitions any more. However it also didn't show "free space" on that drive so I was unable to create a new partition. Even after a reboot and restarting the installation, "free space" was not available.

In the end, I had to select "Use entire disk", and then modify the automatically-generated partition layout that Subiquity had provided until it matched what I wanted :-(