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

[Clint Byrum]

Excerpts from piwacet's message of Wed Sep 28 01:43:19 UTC 2011:
> Apologies if I'm misunderstanding something, but I'm not sure this bug
> is fixed in Oneiric.
> 
> I've tested this in virtualbox with both the server 64-bit beta2 and the
> daily build server 64-bit for Sept. 27th.  If I've hit this same
> problem, it's 100% reproducible.
> 
> Two virtual disks, with /dev/sda1 /dev/sdb1 as raid 1 /dev/md0 for /.
> /dev/sda2 /dev/sdb2 as raid 1 /dev/md1 for swap.
> 
> If I "disconnect" one of the drives, on booting the grub countdown
> appears, and then the screen goes black.  The only response I can get
> from the machine is if I blindly press 'enter', then type 'reboot', then
> press 'enter' again, which causes the virtual computer  to reboot.  It
> doesn't matter which of the 2 disks I 'disconnect.'
> 
> So far, this has happened 100% of boot attempts.  If I reattach the
> disk, it boots fine.
> 
> Apologies if I've misunderstood something.  I can do some virtualbox
> testing if that would help.


piwacet, I've done quite a few test runs doing exactly as you say, and
never been dropped to initramfs. Also I've never had the screen go black
on me. I have been testing with KVM though, not virtualbox.

Can you make sure that the kernel commandline has no "quiet" argument,
and also has 'nomodeset' so we get a text bootup? Its very odd that it
is all black.

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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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