During rescue disk, there can be problems with grub-installation if we are not able to ‘chroot’ in the correct OS environment.
so, if the rescue mode of a Linux OS allows you to run grub from the command line, then installing grub can be done like this
grub-install /dev/sda –root-directory=/mnt/boot
for this, MBR is on /dev/sda and the boot directory with the grub files is located/mounted at /mnt/boot
Rescue Disk is quite different from Linux Rescue Mode.
Rescue Disk is similar to LiveCD
The above command works in Rescue Disk as it does not contain chroot
To install grub in rescue mode.
1. Please find hard-disk name(sda or sdb)
2. enter into the partition
chroot /mnt/sysimage –> hard-disk mounted under this path while server in rescue mode.
3. grub-install /dev/sda
The above cmd for re-install grub boot loader.
The above fix is to install Grub in Linux Rescue Mode