[Bug 2146165] [NEW] Dracut kernel command line parameters not added for software RAID array assembly

[Chris Siebenmann]

Public bug reported:

In the current 26.04/resolute daily ISO images, if you configure a
system with its root on software RAID (for example, with mirrored
disks), the result will fail to boot and time out. The direct cause of
the failure is that the initramfs does not assemble to the software RAID
array of the root filesystem.

My analysis of the cause:

In the current server 26.04 environment, subiquity and the Ubuntu
installer process install a system that uses a Dracut-based initramfs.
In its stock configuration, this initramfs will only assemble RAID
arrays that have been specified on the kernel command line via
'rd.md.uuid=...' parameters (as far as I can see, and this is the
observed behavior). Subiquity doesn't put anything on the kernel command
line, neither specific rd.md.uuid settings nor 'rd.auto=1' to trigger
auto-assembly of everything. Adding a suitable rd.md.uuid= parameter
causes everything to work properly, including from first boot if you
partially auto-install things.

(And when the boot hangs, you can wait for it to time out into the
rescue shell, do 'mdadm -A /dev/md0', and exit to continue into a
regular boot, so the software RAID array itself is definitely properly
built.)

** Affects: subiquity (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/2146165

Title:
  Dracut kernel command line parameters not added for software RAID
  array assembly

Status in subiquity package in Ubuntu:
  New

Bug description:
  In the current 26.04/resolute daily ISO images, if you configure a
  system with its root on software RAID (for example, with mirrored
  disks), the result will fail to boot and time out. The direct cause of
  the failure is that the initramfs does not assemble to the software
  RAID array of the root filesystem.

  My analysis of the cause:

  In the current server 26.04 environment, subiquity and the Ubuntu
  installer process install a system that uses a Dracut-based initramfs.
  In its stock configuration, this initramfs will only assemble RAID
  arrays that have been specified on the kernel command line via
  'rd.md.uuid=...' parameters (as far as I can see, and this is the
  observed behavior). Subiquity doesn't put anything on the kernel
  command line, neither specific rd.md.uuid settings nor 'rd.auto=1' to
  trigger auto-assembly of everything. Adding a suitable rd.md.uuid=
  parameter causes everything to work properly, including from first
  boot if you partially auto-install things.

  (And when the boot hangs, you can wait for it to time out into the
  rescue shell, do 'mdadm -A /dev/md0', and exit to continue into a
  regular boot, so the software RAID array itself is definitely properly
  built.)

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