Ubuntu 22.04 is unable to boot from degraded software raid

[Bjarne Schmidt]

The new autoinstall installer which deprecated the previously used debian-installer supports the creation of an raid array during setup (in my case raid1).
Also as part of the installer the /dev/md0 device is registered as Physical Volume in LVM, a Volume Group is being created and a Logical Volume is created which will be mounted at "/" for the root filesystem.

Creating such an array works fine and results in a flawlessly working system. After the installation I verified that the array is in sync by issuing "cat /proc/mdstat".

To simulate a failure of one disk I erased one of the disks completely and rebooted the system.

The expected behaviour would be: The system boot's normally since there is still one disk available.

The actual behaviour: The system is stuck during boot displaying the following relevant messages:

"Begin: Mounting root file system ... Begin: Running /scripts/local-top ... Volume Group "VG" not found"
"Cannot process volume group VG"
"Gave up waiting for root file system device"

What helped resolving the issue (before wiping one of the disks):
  echo "sleep 60" > /etc/initramfs-tools/scripts/init-premount/init-mdfix
  chmod 744 /etc/initramfs-tools/scripts/init-premount/init-mdfix
  update-grub
  update-initramfs -u

I assume the system is trying to find the root file system but this is not yet available since the raid array is taking too long to initialize after one of the disks has been wiped.

After applying the above fix and wiping one of the disks the system booted normally after waiting for 60 seconds. This seems to be enough for the raid to initialize in a degraded state.

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Libera.chat.

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[Paul White (paulw2u)]

Making the assumption that Ubuntu Server is being installed I'm retasking this to the new installer - subiquity.

[Dan Bungert (dbungert)]

Thanks for the bug report.

I can see similar results outside of autoinstall construction, so I'm updating the title to be more generic.

[Ubuntu QA Website (ubuntuqa)]

This bug has been reported on the Ubuntu ISO testing tracker.

A list of all reports related to this bug can be found here:
http://iso.qa.ubuntu.com/qatracker/reports/bugs/2004485