Q. How do I copy MBR from one hard disk to another hard disk under Debian Linux? I need to do this because of RAID 1 configuration.
A. To copy MBR simply use dd command. dd command works under all Linux distros and other UNIX like oses.
dd command to copy MBR
Type dd command as follows:
dd if=/dev/sda of=/dev/sdb bs=512 count=1
Above command will copy 512 bytes (MBR) from sda to sdb disk.
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- Last Updated: 09/20/07
{ 6 comments… read them below or add one }
This is correct for EXACTLY the same partition sizes. In the case you want the MBR only on a drive that has a root partition of a different size then issue the same command with a smaller block size.
dd if=/dev/sda of=/dev/sdb bs=446 count=1
Thus preserving the partitioning schema.
Right… be VERY careful with doing this w/ two discs with different size partitions! In fact, the safest way to backup/restore JUST THE MBR:
dd if=/dev/sda of=mbrbackup bs=512 count=1
To restore the MBR (on to the same drive or any drive):
dd if=mbrbackup of=/dev/sdb bs=446 count=1
Caiken is right! BEWARE of using the above dd line on two discs that don’t have IDENTICALLY sized partitions! You will lose data!
Here’s what I do to copy just the MBR from a hdd:
dd if=/dev/sda of=mbrbackup bs=512 count=1
Now to restore the image to any hdd:
dd if=mbrbackup of=/dev/sdb bs=446 count=1
Thanks a lot, this was just the kind of short note I was looking for ,)
MBR is 512 or 446 bytes?
MBR is divided into 3 sections
1. Bootstrap . 446 bytes
2. Partition table. 64 bytes
3. Signature. 2 bytes