[Bug 778520] Re: install on degraded raid1 does not boot, drops to initramfs shell

[Galen Seitz]

I am also experiencing problems related to booting with a degraded md
RAID1 array.  I performed a clean install of 64 bit Mythbuntu 11.10 onto
a single disk on an i3 2100 system.  Note that I have configured this
system for UEFI booting.  Later I added a second disk, performing the
following steps:

Installed Seagate ST31000528AS Barracuda 7200.12 1TB drive.
Partitioned as single GPT partition using parted.  
Created RAID1 array with single disk.
  mdadm --create --verbose /dev/md0 --level=mirror --raid-devices=2 /dev/sdb1 missing
Created ext4 filesystem on /dev/md0 using mkfs.ext4.  
Used blkid device to determine UUID.
Added entry in /etc/fstab to mount filesystem using UUID.  Mount point
of /mythtv/drive0.
Created mount point using mkdir.

After adding the disk, booting gives me a blank screen and never
displays any messages.  This is with set gfxpayload=$linux_gfx_mode,
quiet, and splash.  If I remove those, the screen stays blank for ~20
seconds, then the busybox/initramfs screen is displayed.  Once busybox
is displayed, a switch to vt7 reveals the degraded RAID messages.  In
both cases the kernel option vt.handoff=7 is being passed.

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https://bugs.launchpad.net/bugs/778520

Title:
  install on degraded raid1 does not boot, drops to initramfs shell

Status in “initramfs-tools” package in Ubuntu:
  Invalid
Status in “mdadm” package in Ubuntu:
  Fix Released
Status in “initramfs-tools” source package in Natty:
  Invalid
Status in “mdadm” source package in Natty:
  Fix Committed

Bug description:
  Yesterday I did a fresh install of Natty amd64. I used the PXE
  installer so all packages are up to date right after installation.

  I partitioned the disk to have two software raid1 devices. One for swap, one for / with xfs.
  Installation completed successfully, grub was installed to MBR.

  The system has a >95% failure rate in booting.
  At first it would hang on a purple screen. I blindly typed "reboot" at this screen, which worked. So I figured out that it would boot to a shell but not show it.
  Then, I added "nosplash" to the kernel command line and removed "quiet".

  This revealed that the system drops into a BusyBox shell labled "initramfs" when booting fails.
  Unfortunately, I cannot tell whether it shows any errors on screen because the BusyBox shell resets the screen buffer, CTRL+PageUp does not work.

  Please help me how to figure out what is wrong. Either tell me which log file I can search for the very first booting messages OR release a package update which fixes the screen-clearing of the initramfs shell.
  If you do that I will take the effort of doing the 10-20 boot attempts to get to the point where I can update the packages...
  If the initramfs-boot-process is logged anywhere I can check the log files without getting the system to boot through a bootable USB stick...

  ==== SRU Justification ====

  IMPACT: Users who install on a degraded RAID1 or who lose a disk drive
  will be unable to boot.

  TEST CASE:

  1. Install a natty system with root on a software RAID1
  2. After booting once, shutdown
  3. remove one disk entirely
  4. boot the system, it may drop to initramfs, or it may boot degraded
  5. reboot, this time it should reliably drop to initramfs
  6. poweroff and add the disk in again, it should now boot degraded
  7. install updated mdadm
  8. repeat steps 2-5 , it should pass and NOT drop to initramfs

  REGRESSION POTENTIAL: The fix that has been uploaded to oneiric
  already takes care to err on the side of responding to degraded
  arrays. Still mdadm is very sensitive and so probably needs a bit of
  extra testing to ensure that it works properly, including passing the
  usual RAID1 iso install tests (with the additional step of installing
  the mdadm package from proposed right after install)

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