Steps to rectify the Corrupted MBR on RHEL 5 & 6
Restore MBR in Linux Boot into the Rescue mode. boot:linux rescue Select language, keyboard and skip finding the installation Make a temporary mount point /vxvm and mount the root partition on it. mkdir /vxvm mount -t ext3 /dev/sda1 /vxvm [ where /dev/sda1 is the root partition ] If the disk has a separate boot partition mount it on /vxvm/boot mount -t ext3 /dev/sda2 /vxvm/boot [where /dev/sda2 is the boot partition] Recreate the master boot record (MBR) on the root disk. For the GRUB boot loader : Check contents of /boot/grub/menu.lst or /boot/grub/grub.conf or /etc/grub.conf are correct Use the /vxvm/sbin/grub command to enter into the grub menu to recreate the MBR on the disk # /vxvm/sbin/grub grub> root (hd0,1) grub> setup (hd0) grub> quit