Re: Upgrading a software RAID

[Bill Davidsen <davidsen@tmr.com>]

Thomas Fjellstrom wrote:
> On Tue June 2 2009, Bill Davidsen wrote:
>   
>> Maxime Boissonneault wrote:
>>     
>>>>>> The initrd is the ramdisk which the kernel boots to first, containing
>>>>>> the various modules and utility programs (like mdadm) needed to access
>>>>>> the main root filesytem.  A quick search suggests that you need to run
>>>>>> 'update-initramfs -u' on Ubuntu.  You'll need to boot off the CD and
>>>>>> chroot onto the new array first though - something like:
>>>>>>
>>>>>>  - Boot off CD
>>>>>>  - Assemble the RAID arrays
>>>>>>  - Create a mount point for the new array (mkdir /mnt/newroot)
>>>>>>  - Mount the root filesystem (mount /dev/md1 /mnt/newroot)
>>>>>>  - Mount the proc filesystem (mount -o bind /proc /mnt/newroot/proc)
>>>>>>  - Mount the sys filesystem (mount -o bind /sys /mnt/newroot/sys)
>>>>>>  - Mount the dev filesystem (mount -o bind /dev /mnt/newroot/dev)
>>>>>>  - Chroot to the new array (chroot /mnt/newroot /bin/bash)
>>>>>>  - Mount the boot filesystem (mount /boot)
>>>>>>  - Update the initramfs (update-initramfs -u)
>>>>>>  - Unmount the boot filesystem (umount /boot)
>>>>>>  - Exit the chroot (exit)
>>>>>>  - Unmount the dev filesystem (umount /mnt/newroot/dev)
>>>>>>  - Unmount the sys filesystem (umount /mnt/newroot/sys)
>>>>>>  - Unmount the proc filesystem (umount /mnt/newroot/proc)
>>>>>>  - Unmount the root filesystem (umount /mnt/newroot)
>>>>>>  - Reboot
>>>>>>
>>>>>> That's just from memory though, so watch out for any warnings/errors.
>>>>>> The other issue you _may_ have is the raid5 module missing from the
>>>>>> initrd - you'd best check that raid5 is listed in
>>>>>> /etc/initramfs/modules.
>>>>>>             
>>>>> RAID5 should not be missing, my /home was a RAID5.
>>>>>           
>>>> Yes, but /home is only mounted after it's accessed the root partition.
>>>> It can then read any modules from the root partition, so the raid5
>>>> module could still be missing from the initrd.  I suspect it'll have
>>>> included it though.
>>>>         
>>> I did as you suggested above. I still get the same error message.
>>> I have looked and did not find /etc/initramfs/modules. Instead, I
>>> found /etc/initramfs-tools/modules. In this file, there were a couple
>>> of comment lines explaining how to enable modules.
>>> No modules were included.
>>> I uncommented the "raid1" and added "raid5" and ran the procedure again.
>>>
>>> Still getting the same problem.
>>>
>>> Since the problem seems to be the boot, I will try to do a fresh
>>> install, then restore my backup while keeping the /boot from the fresh
>>> install.
>>>       
>> If this were Fedora I would be using mkinitrd to get the right modules
>> in the boot image, however Ubuntu requires another method, which I don't
>> know well enough to describe. You are probably on the right tract
>> though, getting the modules and mdadm.conf available at boot.
>>     
>
> I assume its more or less like debian, so you just add the modules to 
> /etc/initramfs-tools/modules and run: update-initramfs -uk `uname -r`
>
> then the modules you added to the modules file will be added to the initramfs 
> file, and loaded into the kernel at that stage.
>
>
>   
Is there some explicit action needed to get the mdadm.conf file added to 
the image?

-- 
Bill Davidsen <davidsen@tmr.com>
  Even purely technical things can appear to be magic, if the documentation is
obscure enough. For example, PulseAudio is configured by dancing naked around a
fire at midnight, shaking a rattle with one hand and a LISP manual with the
other, while reciting the GNU manifesto in hexadecimal. The documentation fails
to note that you must circle the fire counter-clockwise in the southern
hemisphere.