Re: status: how to install grub to non-bootable RAID-formatted drive?

["Alexander V. Makartsev" <avbetev@gmail.com>]

On 1/23/26 20:29, D. R. Evans wrote:

> ...
>       So, given all the above, I intend to proceed with:
>       
>       
>       cp -r /dev/ /tmp/RFS/dev/
>       
>       chroot /tmp/RFS /usr/bin/bash
>       
>       grub-install /dev/sda
>       
>       sync
>       
>       exit
>       
>       reboot
>       
>       
>       after I've given people a bit of time to shout at me not to do
>       that if something in what I've written above looks bad. 
>     
    "cp -r /dev/ /tmp/RFS/dev/"  is wrong! Don't do that. 
    Think about it, "cp" command will copy block devices such as
    /dev/sda like files into /tmp/RFS, basically into itself until it
    runs out of free space.
    
    You need to double check if "/dev/sda" is the disk you want to
    recover.
    Commands like: 
        blkid
          ls -la /dev/disk/by-id 
          smartctl -i /dev/sda
          mdadm --misc --detail /dev/md126
    should help you identify it correctly.
    
    Taking everything into consideration the right sequence of commands
    should be:
        mkdir /tmp/RFS
          mount /dev/md126 /tmp/RFS    #Mount root filesystem
          mount --bind /dev /tmp/RFS/dev    #Mount bind real /dev to
      populate chroot-ed /dev
          mount --bind /proc /tmp/RFS/proc    #Mount bind real /proc to populate chroot-ed /proc
        mount --bind /sys /tmp/RFS/sys    #Mount
      bind real /sys to populate chroot-ed
      /sys
        chroot /tmp/RFS /usr/bin/bash    #Change
      root into directory /tmp/RFS
          grub-install --target=i386-pc /dev/sda    #Install grub stage
      1 and stage 2 MBR bootloader into /dev/sda and /boot
          sync    #Sync filesystems
          exit    #Exit chroot
          umount /tmp/RFS/dev
          umount /tmp/RFS/proc
          umount /tmp/RFS/sys
          umount /tmp/RFS
          systemctl reboot
    
    Hopefully grub-install will recognize raid partition correctly and
    create working grub config.
    Before exiting chroot you can check "/boot/grub/grub.cfg" for
    filesystem UUIDs and compare them to the output from "blkid"
    command:
        cat /boot/grub/grub.cfg | grep -iE --
      "--set=root"
      ...
      search --no-floppy --fs-uuid --set=root
      155380c9-4578-4a85-80c3-a78c7ffa7cb1
      ...
          blkid --uuid 155380c9-4578-4a85-80c3-a78c7ffa7cb1
      /dev/nvme0n1p5
    
    "/dev/nvme0n1p5" is my boot partition, your UUIDs and blkid output
    will be different.

--

 With kindest regards, Alexander.

 Debian - The universal operating system
 https://www.debian.org