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Backup & Restore the Master Boot Record

Some days ago I had to recover the Master Boot Record (MBR) of a damaged hard disk.

The MBR is the first 512 bytes of a storage device. It contains an operating system boot loader and the storage device’s partition table.

If you need to make a backup of the MBR type the following command:

dd if=/dev/sda of=/root/mbr.img bs=1 count=512

You only have to change sda with the device name that correponds to your hard disk.

To restore it:

dd if=/root/mbr.img of=/dev/sda bs=1 count=512

And as before, change sda with the device name that corresponds to the hard disk you are going to restore the MBR to.

The partition table has a size of 64 bytes and it starts at position 0x01BE (446) so if you want to only restore it:

dd if=/temp/mbr.img of=/dev/sda skip=446 seek=446 bs=1 count=64

It may come in handy when you mess with the partition table. Yes, that moment where you press w in fdisk and immediately regret it ;)

For more information the Wikipedia MBR article is very detailed.

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