Kernel Panic - not syncing: VFS: unable to mount root fs on unknown-block (0,0)

[Shwetang Buch]

Hello,

Facing problem in CentOS 7 while booting. Getting below error:

Kernel Panic - not syncing: VFS: unable to mount root fs on unknown-block (0,0)

under rescue mode, installing grub didn't work on XFS filesystem hence formatted /dev/sda1 with ext4 filesystem and mounted under /boot (chrooted to /mnt/sysimage).

This gives another error as below:

# grub2-install --force -s /dev/sda1

error: embedding is not possible but this is required for cross-disk install

Right now there is nothing inside /boot. 

Please share with me how to install grub2 bootloader from scratch in the system..

p.s. there is data on the server which need not to touch...

Regards,

Shwetang Buch