MBR扇区故障
1：mkdir /GEN
2: mount /dev/sdd1 /gen
3: dd if=/dev/sda of=/gen/sda.mbr.bak bs=512 count=1
5: dd if=/dev/zero of=/dev/sda bs=512 count=1
6: reboot
7: mkdir /gen
8: mount /dev/sdd1 /gen
9: dd if=/gen/sda.mbr.bak of=/dev/sda bs=512 count=11
10:reboot
GRUB引导故障
1:MBR中的GRUB引导程序破坏 (重装grub程序）
dd if=/dev/zero of=/de/sda bs=200 count=1
reboot
chroot /mnt/sysimage
grub2-install /de/sda
sync
sync
exit sync
exit sync
exit
2： grub.cfg文件丢失，引导配置有误
mkdir /a
cp /boot/grub2/grub.cfg /a
rm -rf /boot/grub2/grub.cfg
chroot /mnt/sysimage
cp /a/grub.cfg /boot/grub2
sync
exit
3: 误删/boot/
rm-rf /boot/
reboot
chroot /mnt/sysimage
mkdir /media/cdrom
mount /dev/sr0 /media/cdrom
ls /boot/
rpm -ivh /media/cdrom/Packages/kernel-字符串 --force
grub2-install /dev/sda
grup2-mkconfig > /boot/grup2/grup.cfg
reboot