sudo mdadm -E /dev/sda5
sudo mdadm -Av /dev/md0 --uuid=47b7dc92:0dd53670:01d7672c:70b7c4cb /dev/sda5 /dev/sdb5
mdadm -Ds >> /etc/mdadm/mdadm.conf
update-initramfs -u
sudo apt-get install lvm2 mdadm
mdadm --create /dev/mdx --level=1 --raid-devices=2 /dev/sdax missing
vgcreate vg0 /dev/mdx --physicalextentsize 32M
sudo lvcreate -L100G -n qihua vg0
sudo update-initramfs -u #Make it loaded by ram fs.
sudo mdadm --zero-superblock /dev/sda[x]
sudo mkfs.ext4 -m0 /dev/vg0/qihua
sudo mkfs.ext4 -m0 /dev/vg0/akhome
sudo mkdir /media/lvm
sudo mount /dev/mapper/vg0-akhome /media/lvm/
sync to temp directory.
sudo rsync -av --exclude=lost+found --exclude='/media/*' --exclude='/dev/.[isu]*' --exclude='/lib/init/rw/*' --exclude='/lib/modules/*/volatile/*' --exclude='/proc/*' --exclude='/sys/*' --exclude='/home/*' --exclude='/var/lock/*' --exclude='/var/run/*' / /media/lvm/
rsync -av --exclude=lost+found --exclude=/media/* --exclude='/dev/.[isu]*' --exclude='/lib/init/rw/*' --exclude='/lib/modules/*/volatile/*' --exclude='/proc/*' --exclude='/sys/*' --exclude='/home/*' --exclude='/var/lock/*' --exclude='/var/run/*' / /media/lvm/
sudo cp /proc/cmdline /media/lvm/proc/
sudo cp /proc/modules /media/lvm/proc/
sudo chmod a+w /media/lvm/proc/cmdline,
sudo vi /media/lvm/proc/cmdline change: root=/dev/mapper/vgx-xxxxxx ro
sudo chmod a+w /media/lvm/etc/fstab
sudo vi /media/lvm/etc/fstab
sudo chmod a+w /media/lvm/boot/grub/grub.cfg
sudo vi /media/lvm/boot/grub/grub.cfg
sudo chroot /media/lvm
update-initramfs -c -k `uname -r`
sudo grub-install --root-directory=/media/lvm /dev/sdx