The Master Boot Record (MBR) is the initial section of a disk that handles bootloaders, such as GRUB, to enable your system to boot into an operating system. It's crucial to maintain an MBR backup, as GRUB can be re-generated if lost or deleted.
To restore the MBR, you'll need to use dd, a command-line tool that can also create backups. If your Linux system is unbootable, you must use a secondary system, such as an Ubuntu installer disk, to load and restore your MBR backup.
Related: How to back up Master Boot Record (MBR) in Linux
Related: How to recover lost GRUB bootloader in Linux
Steps to restore Master Boot Record from dd backup:
- If your system won't boot, use a Live CD or USB drive to access Linux.
- Open the terminal.
- Verify that your MBR backup is correct.
$ file mbr.bak mbr.bak: DOS executable (COM) $ cat mbr.bak �c������t��pt���y|1��؎м ��d|<�t��R��t��}��|�A��U�ZRr=��U�u7��t21��D@�D��D�f�\|f�f�`|f�\ Z������}�f�ƈd�@f�D�������@�����f�f�`|f �uNf�\|f1�f�4��1�f�t;}7����0�����Z�ƻp��1۸�r��`���1�������a�&Z|��}���}�4��}�.���GRUB GeomHard DiskRead Error ����<u��
- List the available disks and find the one with the damaged master boot record.
$ lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT loop0 7:0 0 55.4M 1 loop /snap/core18/1932 loop1 7:1 0 55.4M 1 loop /snap/core18/1944 loop2 7:2 0 217.9M 1 loop /snap/gnome-3-34-1804/60 loop3 7:3 0 219M 1 loop /snap/gnome-3-34-1804/66 loop4 7:4 0 51M 1 loop /snap/snap-store/498 loop5 7:5 0 62.1M 1 loop /snap/gtk-common-themes/1506 loop6 7:6 0 51M 1 loop /snap/snap-store/518 loop7 7:7 0 64.8M 1 loop /snap/gtk-common-themes/1514 loop8 7:8 0 31.1M 1 loop /snap/snapd/10492 loop9 7:9 0 31.1M 1 loop /snap/snapd/10707 sda 8:0 0 20G 0 disk ├─sda1 8:1 0 1M 0 part ├─sda2 8:2 0 513M 0 part /boot/efi └─sda3 8:3 0 19.5G 0 part / sr0 11:0 1 1024M 0 rom
- Use dd to restore the disk's master boot record from the backup.
$ sudo dd if=mbr.bak of=/dev/sda [sudo] password for user: 0+1 records in 0+1 records out 446 bytes copied, 0.00284831 s, 157 kB/s
- Confirm that your MBR has been properly restored.
$ sudo head -c 446 /dev/sda �c������t��pt���y|1��؎м ��d|<�t��R��t��}��|�A��U�ZRr=��U�u7��t21��D@�D��D�f�\|f�f�`|f�\ Z������}�f�ƈd�@f�D�������@�����f�f�`|f �uNf�\|f1�f�4��1�f�t;}7����0�����Z�ƻp��1۸�r��`���1�������a�&Z|��}���}�4��}�.���GRUB GeomHard DiskRead Error ����<u��
- Restart your system to ensure it's functioning correctly.

Author: Mohd Shakir Zakaria
Mohd Shakir Zakaria is a skilled cloud architect with a background in development, entrepreneurship, and open-source advocacy. As the founder of Simplified Guide, he helps others understand the complexities of computing, making tech concepts accessible to all.

Mohd Shakir Zakaria is a skilled cloud architect with a background in development, entrepreneurship, and open-source advocacy. As the founder of Simplified Guide, he helps others understand the complexities of computing, making tech concepts accessible to all.
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