Grub2 and and mdraid

[Patrick Begou]

Hi,

for a while now I'm trying to set up grub to boot on a md array without any 
success. The system is actualy runing with:
/dev/sda2 mounted on /boot
/dev/sda3 a physical volume and /dev/mapper/pve-root mounted on /root
(proxmox distribution)

I've added a second disk /dev/sdc to move to a RAID1 config.

/dev/sdc2 is part of a degraded raid1 array /dev/md2  and /dev/md2 is an ext4 
filesystem for /boot
/dev/sdc3 is part of a degraded raid1 array /dev/md3  and /dev/md3 is a lvm 
physical volume.
On dev/md3 there is a logical volume /dev/mapper/pveraid-root, with ext4 
filesystem to mount as /

System has been copied from sda to sdc.

I try to set-up grub with:

mount /dev/md2 /mnt/boot
mount /dev/pveraid/root /mnt/root
cp -dpRx / /mnt/root
cp -dpRx /boot/* /mnt/boot
update-grub  -o /mnt/boot/grub/grub.cfg
grub-install --no-floppy --modules="biosdisk raid mdraid1x ext2 part_msdos 
part_gpt" --boot-directory=/mnt/boot --recheck /dev/sdc

I've added a menu /etc/grub.d/09_swraid1_setup to try to boot /dev/sdc using the 
uuids as described in 
http://unix.stackexchange.com/questions/196212/required-grub-modules-for-booting-on-mdadm-raid1
#!/bin/sh
exec tail -n +3 $0
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.
menuentry 'proxmox with RAID1' --class proxmox --class gnu-linux --class gnu 
--class os {
  load_video
  set root=(mduuid/c65cfbac-c874-4d3b-9b43-47e9d539db35)
  echo 'Loading Proxmox with RAID...'
  linux /vmlinuz-2.6.32-32-pve root=64342e2a-867b-421a-b5e1-062558c782f0 ro 
quiet
  echo 'Loading initial ramdisk...'
  initrd /initrd.img-2.6.32-32-pve
}

Or without the UUIDs as discribed in 
https://www.howtoforge.com/how-to-set-up-software-raid1-on-a-running-system-incl-grub2-configuration-debian-squeeze-p2
#!/bin/sh
exec tail -n +3 $0
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.
menuentry 'proxmox with RAID1' --class proxmox --class gnu-linux --class gnu 
--class os {
  load_video
  insmod raid
  insmod raid1
  insmod mdraid
  insmod part_msdos
  insmod ext2
  set root='(md/2)'
  echo 'Loading Proxmox with RAID...'
  linux /vmlinuz-2.6.32-32-pve root=/dev/mapper/pveraid-root ro quiet
  echo 'Loading initial ramdisk...'
  initrd /initrd.img-2.6.32-32-pve
}


But every time I get in the a rescue shell, saying the disk is not found. In the 
"ls" command of the rescue shell no md devices seams available.

When I try to boot on the raid config, I set /dev/hdc to be the first in the 
device order at boot time via the bios.

I can of course restart the server on /dev/sda  to keep it runing.

I do not find any help in the grub2 manual nor on the web, just an old 
discussion (2013) on a problem with degraded arrays...

Thanks for your advices

Patrick



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