20.04 install software raid fails. SSD's have identical WWN's.

[jbraamse]

I want to install Ubuntu server 20.04.1 LTS (latest) with software raid1.
(Subiquity 20.09.1+git1.67496d12)
During install I define root, swap and data partitions on both SSD's.
When done, I proceed to the next step and then the installer crashes.
The logfiles show me that disks have the same WWN, serial numbers are not the same.
Disks are equal size and brand; Samsung 256GB SSD SATA6

I found bug #1876848 and I decided to use one Samsung SSD and one Micron SSD(similar size).
This works fine.

My attempt to find a workaround:

I used mdadm to remove the Micron drive and tried to replace it by a Samsung drive (correctly partitioned).
When adding a partition to an mdx drive it says "resource busy".
Tried to use the -f option, same message: "resource busy".
I am afraid mdadm doesn't like the identical WWN's.

bug #1876848 suggests this problem was solved.
This may be a slightly different problem, please investigate.

A crash report log is attached.
There are lots of logfiles, if you need more, tell me which ones you need.

[jbraamse (jbraamse)]

Apologies for this:
I assumed mdadm has this problem too, but that's a mistake.
mdadm can handle hdd's when they have identical WWN's.
The message "device or resource busy" is caused by something else.

So it's clearly a subiquity bug.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[discots (discots)]

I confirm this issue. We have found at least 2 systems with this issue in our environment where during the installation the "Info ..." in Subiquity on the the SSD shows the same WWN for 2 disks, and as such fails to set up SW RAID.
As this was no problem in the previous installer, nor on mdadm, there is no doubt this should be a confirmed bug on Subiquity. I'm actually surprised this has been untouched in 13 months.

[Michael Hudson-Doyle (mwhudson)]

As it happens I've just started to work on this. It's a duplicate of another bug though, I'll mark this as such.