Starting
I had to download linux system on my laptop and I chose Debian. I had been playing around LVM on my computer so I decided to try to install Debian on LVM.
I downloaded .iso file on USB, plug it into my laptop and started installation. Everything was fine but after reboot everything I saw was a blinking cursor at the beginning of the black screen. I turned off the laptop and tried to boot from another kernel and everything worked. I started to dig into it…
nomodeset, splash, quiet
I read in the internet that new linux systems set videomode in kernel. So all the video-drivers are in kernel instead of X-server. It makes possible to show beautiful images during system boot. But not all the machines support this and it leads to errors (black screen and lags). So I needed to set a nomodeset option in /boot/grub/grub.cfg in /boot/vmlinuz* line. I could also edit my config file in grub menu by pressing ‘e’. I entered the system. The problem was that after executing grub-update all the options would be restored. I found out about GRUB_CMDLINE_LINUX_DEFAULT and GRUB_CMDLINE_LINUX variables. I needed to set them in the /etc/default/grub file.
GRUB_CMDLINE_LINUX_DEFAULT sets options in /boot/vmlinuz* line for normal boot. GRUB_CMDLINE_LINUX sets options in /boot/vmlinuz* line for recovery boot.
So I changed them to:
GRUB_CMDLINE_LINUX_DEFAULT="quiet nomodeset splash"
GRUB_CMDLINE_LINUX=""
Also I added splash and quiet options.
splash option makes it possible to show boot images like this:
quiet option supresses verbose output about starting the system.
Setting root directory
Downloading my system I made three partitions:
- /boot 1GB
- LVM partition 324GB
- Temporary root partition 16GB
After it I created /dev/vg1/lv_home logical volume for /home and /dev/vg1/lv_root logical volume for /root. I mounted lv_home and copied /home there. After it I added mount point in the /etc/fstab. Then I mounted lv_root and made a copy of the system:
rsync -aHAX / /mnt/new-root -v --one-file-system
then I mounted /dev, /run, /proc and /sys with –bind option there.
for i in /proc/ /sys/ /dev/ /run/; do mount --bind $i /mnt/new-root/$i; done
chroot /mnt/new-root
But the problem was that my kernel needed to be recompiled for LVM to be loaded via grub. I had initrd files in the /boot directory (I will write about initrd in the future), so I ran:
update-grub
cd /boot
for i in `ls initrd.img-*`; do dracut -v $i `echo $i | sed s/initrd.img-//g` --force; done
I used this website - https://casp.ru/?p=55.
But the problem wasn’t solved :(. I rebooted and ran
lsblk
And my / wasn’t on lv_root. I realized that I needed to mount /boot directory because all the newly created grub configuration files was stored on lv_root. I mounted /boot directory
mount --bind /boot /mnt/new-root/boot
and did the same thing. After reboot everything worked!
Troubleshooting
I decided to delete that temporary partion and left only /boot and LVM partition. After reboot I ran into problems… Grub didn’t know how to find root partition - https://unix.stackexchange.com/questions/329926/grub-starts-in-command-line-after-reboot. So I ran:
ls
found lvm partition and
set prefix=(lvm/vg1-lv_root)/boot/grub
set root=(hd1,2)
insmod linux
insmod normal
normal
boot
After it I joined my system and realized that I didn’t update /boot partition, so I ran (because /boot partition was mounted on /boot/efi):
grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=debian --recheck --debug /dev/sdb
update-grub
and everything worked!