http://www.shell-fu.org/lister.php?id=803
Backup MBR:
dd if=/dev/sda of=/root/mbr.img bs=1 count=512
Restore MBR:
dd if=/root/mbr.img of=/dev/sda bs=1 count=512
Restore only bootstrap (part of MBR):
dd if=/temp/mbr.img of=/dev/sda bs=1 count=446
Restore only partition table (part of MBR):
dd if=/temp/mbr.img of=/dev/sda skip=446 seek=446 bs=1 count=64
http://community.livejournal.com/ru_linux/2544765.html?thread=36215677#t36215677
# cat /sys/block/sda/sda1/{start,size}
/sys/block/sda/sda1/start:63 /sys/block/sda/sda1/size:2120517
# fdisk /dev/sda
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First sector (63-312581807, default 63):
Using default value 63
Last sector, +sectors or +size{K,M,G} (63-312581807, default 312581807): +2120516