[arch-general] Why Is My RAID Installing Failing?

[Eric Bélanger]

On Mon, Jan 11, 2010 at 12:52 PM, Carlos Williams <carloswill at gmail.com> wrote:
> OK - I am once again attempting to use Arch install for 2010 on my
> system which has two identical hard drives and I simply want to mirror
> both drives in a RAID1 array. I have read the Wiki so much at this
> point it has become memorized. I am NOT using LVM or anything, just a
> Arch user who wants RAID1, very simple, right? Well wait, it gets
> easier. I am not even attempting to add my MBR /dev/sda1 (/boot) to
> the RAID1 array. Crazy simple, huh? You might even ask well why am I
> even asking for help then...well because I hate the Arch installer and
> not because its CLI only. No, I love the simplicity of the installer
> and not being graphical but the RAID configuration is a complete mess.
>
> I am booting from a fresh 2009.08 Netinstall ISO disk. I select the
> 1st option and login as root (requires no password). Before I just
> junp into the installer (/arch/setup), I need to configure a few
> things:
>
> 1 - I use 'cfdisk' to configure /dev/sda & /dev/sdb.
>
> - /dev/sda1 = 4096 MB (bootable) 83
> - /dev/sda2 = The rest of the disk (selecting 'fd' type)
>
> - /dev/sdb1 = 4096 MB (SWAP) 82
> - /dev/sdb2 = The rest of the disk (selecting 'fd' type)
>
> 2. I need to load my RAID1 modules using the following command:
>
> #modprobe raid1
>
> 3. Now I need to create my RAID1 mirror using the following command:
>
> #mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sda2 /dev/sdb2
>
> 4. Check to make sure the RAID is rebuilding and both devices show [UU]
>
> #cat /proc/mdstat
>
> So now everything is working fine and going as it should be via the
> Wiki. Now the Wiki in my opinion is way too bloated and tries to do
> too much so I am cutting and pasting what I feel applies to me. Which
> is why I am showing you everything I am doing here in this email to
> see why I am failing.
>
> Now I need to update the /etc/mdadm.conf file with my new RAID1 I
> created with the following command:
>
> #mdadm -D --scan >> /etc/mdadm.conf
>
> And I also verify that my info was correctly populated into the
> /etc/mdadm.conf file using the following command:
>
> #cat /etc/mdadm.com
>
> So now I am ready to run the /arch/setup command from the CLI to
> begine configuring the install / my new system.
>
> 1 - Select Source = I configure my install method and all my network variables
> 2 - Set Clock = I configure my Time Zone and stuff
> 3 - Prepare Hard Drive(s) = Here I can skip to section sub menu 3
> since I already did most of this above. I simply now just select mount
> points for my existing partitions:
>
> sda1 = /boot (ext3)
> sdb2 = swap (swap)
> md0 = /         (ext4)
>
> 4 - Select Packages = I select the base packages and what I feel is
> required for my setup.
> 5 - Install packages = I let the system download and install the
> packages from my mirror.
> 6 - Configure System = This is where I feel my confusion comes into
> play. Perhaps I am missing something:
>
> */etc/rc/conf = I simply add the changes below:
> - In 'Hardware' section add "MODULES=(md_mod raid)
> - HOSTNAME="mypc"
> - "sshd" added to the "DAEMONS" line
>
> */etc/mkinitcpio.conf
> - add 'mdadm' on the 'HOOKS' line after "sata" & before "filesystems"
> as noted in the Wiki.
>
> */etc/resolv.conf
> - Check to make sure DNS looks good...it does.
>
> */etc/hosts
> - Add my FQDN here as follows:
> 127.0.0.1      mypc.mydomain.tld    mypc
>
> *Root-Password
> - Create a secure root password.
>
> Now that is it. I select 'Done' and let it build 'initcpio' images.
>
> 7 - Install Bootloader = Here I select "Grub" and then review the
> default menu.lst it produces. I then select /dev/sda to install Grub
> on.
> "Grub was successfully installed"
>
> Now I am done and back at the bash shell logged in as root.
>
> I then run the following command:
>
> #cp -a /etc/mdadm.conf /mnt/etc/mdadm.conf to make sure when the
> system boots, it is aware of my RAID1 mirror.
>
> Now I reboot because I assume I am done.
>
> Here is my error:
>
> ::Running Hook [mdadm]
> Waiting 10 seconds for device /dev/md0
>
> Root device '/dev/md0' doesn't exist, attempting to create it
> ERROR: Failed to parse block device for ids for /dev/md0
> ERROR: Unable to detect or create root device /dev/md0
> You are being dropped into a recovery shell
> Type reboot to reboot
> Type exit to try and continue booting
>
> If the device /dev/md0 gets created while you are here, try adding
> 'rootdelay=10 or higher to the kernel command line.
> ramfs$ _
>

In /etc/mkinitcpio.conf, add
raid1 raid456
to the MODULES array and regenerate your initcpio image.  That should
fix it if it's the same (known ) problem that I think it is.