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I was following this tutorial: http://www.howtoforge.com/how-to-set...buntu-11.10-p2

and I tried to recreate it for ubuntu 12.04 since a lot of things have changed.

Don't be scared with the length of this thread. It is really only the first two pages of the tutorial in a nutshell. It is the procedure I followed while I was trying to create a raid-1 on a running system that now has two identical disk drives.

Please try to follow it to see what is wrong because the tutorial of raid-1 for ubuntu 12.04 would be very useful and now is missing!

This is the procedure (not working yet):
Code:
just to see which disks are detected

        cat /proc/diskstats

        or

        sudo lshw -c storage -c disk



Typically is sdb

Format your drive using the disk utility

    In Disk Utily use default Master Boot Record



Take all the partition configuration from sda and put it in sdb. We want an exact copy so this is the first step

        sudo sfdisk -d /dev/sda | sfdisk --force /dev/sdb

                

To format the drive

  sudo fdisk /dev/sdb



for all partitions (sdb1 and sdb5) do the following:

                Type 't' to change the partition's system id

                Choose partition number

                Type 'L' to list all codes

                choose the code "fd" for Linux raid auto

                finally on the main menu type 'w' to write (save) all the changes and quit

        

install mdadm

        sudo apt-get install mdadm

        

To make sure that there are no remains from previous RAID installations on /dev/sdb, we run the following commands:

        sudo mdadm --zero-superblock /dev/sdb1

        sudo mdadm --zero-superblock /dev/sdb5



create raid-array

        //sudo mdadm --create --verbose --auto=yes /dev/md0 --level=1 --raid-devices=2 /dev/sda /dev/sdb        

        sudo mdadm --create /dev/md0 --level=1 --raid-disks=2 missing /dev/sdb1

        sudo mdadm --create /dev/md1 --level=1 --raid-disks=2 missing /dev/sdb5

        

to verify execute this:

        cat /proc/mdstat

        should now show that you have two degraded RAID arrays ([_U] or [U_] means that an array is degraded while [UU] means that the array is ok)

        

Create filesystems on raid arrays

        //sudo mkfs.ext4 /dev/md0

        sudo mkfs.ext2 /dev/md0

        sudo mkswap /dev/md1



Set new mdadm configuration by first backing up the original

        sudo cp /etc/mdadm/mdadm.conf /etc/mdadm/mdadm.conf_orig



execute the line below to save to a temporary file

        sudo mdadm --examine --scan > temporary.txt

        copy and paste at the end(append) of this file:

                sudo nano /etc/mdadm/mdadm.conf

                or

                sudo gedit /etc/mdadm/mdadm.conf

        and of course delete temporary file

                sudo rm temporary.txt

                

Next we modify /etc/fstab. Comment out the current /, /boot, and swap partitions and

add new lines for them where you replace the UUIDs with /dev/md0 (for the / partition) and /dev/md5 (for the swap partition), AGAIN don't know for third one

        sudo nano /etc/fstab

        or

        sudo gedit /etc/fstab

        

Next replace /dev/sda1 with /dev/md0 in /etc/mtab:

        sudo nano /etc/mtab

        or

        sudo gedit /etc/mtab

        

Now up to the GRUB2 boot loader. Create the file /etc/grub.d/09_swraid1_setup as follows

        sudo cp /etc/grub.d/40_custom /etc/grub.d/09_swraid1_setup

        sudo nano /etc/grub.d/09_swraid1_setup

        or

        sudo gedit /etc/grub.d/09_swraid1_setup

        Copy paste this inside:

                menuentry 'Ubuntu, with Linux 3.2' --class ubuntu --class gnu-linux --class gnu --class os {

                                    insmod raid

                                    insmod mdraid

                                    insmod part_msdos

                                    insmod ext2

                                    set root='(md/0)'

                                    echo    'Loading Linux 3.2.0-34-generic ...'

                                    linux   /vmlinuz-3.2.0-34-generic root=/dev/md0 ro  quiet

                                    echo    'Loading initial ramdisk ...'

                                    initrd  /initrd.img-3.2.0-34-generic

                }

        Make sure you use the correct kernel version in the menuentry stanza (in the linux and initrd lines). You can find it out by running

                uname -r



Because we don't use UUIDs for our block devices, open /etc/default/grub...

        sudo nano /etc/default/grub

        or

        sudo gedit /etc/default/grub

...and uncomment the line GRUB_DISABLE_LINUX_UUID=true



set BOOT_DEGRADED to true so that the system can boot from a degraded array without asking 

        sudo nano /etc/initramfs-tools/conf.d/mdadm

        or

        sudo gedit /etc/initramfs-tools/conf.d/mdadm



Now run

        sudo update-grub

        

Next we adjust our ramdisk to the new situation:

        sudo update-initramfs -u



Now let's mount /dev/md0 (we don't need to mount the swap array /dev/md5):

        sudo mkdir /mnt/md0

        sudo mount /dev/md0 /mnt/md0

        

Next we change the partition type of /dev/sda5 to Linux raid autodetect and add /dev/sda5 to the /dev/md1 array:

        sudo fdisk /dev/sda

        

SUGGESTION HERE IS TO CREATE A Linux raid autodetect ONLY FOR THE SWAP PARTITION! Does this makes sense or should we do it for the main partition as well??

But even if we try the first attemtp to add the device to the array:

        sudo mdadm --add /dev/md1 /dev/sda5

does NOT succeeed !



Now we copy the contents of /dev/sda1 to /dev/md0        

Attempt to Copy 1:

        cd /boot

        sudo cp -dpRx . /mnt/md0



Attempt to Copy 2:

        sudo cp -dpRx / /mnt/md0



You should now the md0 array in the output of:

        mount

        

Afterwards we must make sure that the GRUB2 bootloader is installed on both hard drives, /dev/sda and /dev/sdb:

        sudo grub-install /dev/sda

        sudo grub-install /dev/sdb

        

reboot