修复linux mbr,linux修复MBR扇区故障解决方案
故障原因病毒、木马等造成的破坏(如硬盘炸弹)
不正确的分区操作、磁盘读写误操作
故障现象找不到引导程序，启动中断
无法加载操作系统，开机后黑屏
解决思路应提前作好备份文件
以安装光盘引导进入急救模式
从备份文件中恢复
修复MBR扇区故障示例：
第一步：添加一块20G硬盘
[root@localhost ~]# fdisk -l
Disk /dev/sda: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000eac35
Device Boot Start End Blocks Id System
/dev/sda1 * 1 26 204800 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 26 1046 8192000 82 Linux swap / Solaris
/dev/sda3 1046 2611 12573696 83 Linux
Disk /dev/sdb: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
第二步硬盘分区
[root@localhost ~]# fdisk /dev/sdb
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0x52d92de3.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u').
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-2610, default 1):
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-2610, default 2610):
Using default value 2610
Command (m for help): p
Disk /dev/sdb: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x52d92de3
Device Boot Start End Blocks Id System
/dev/sdb1 1 2610 20964793+ 83 Linux
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
第三步;创建挂载点和格式化
挂载/dev/sdb1 到 /backup,将MBR扇区备份至此，损坏MBR扇区，重启。
[root@localhost ~]# mkdir /shiyan
[root@localhost ~]# mkfs /dev/sdb1
mke2fs 1.41.12 (17-May-2010)
文件系统标签=
操作系统:Linux
块大小=4096 (log=2)
分块大小=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
1310720 inodes, 5241198 blocks
262059 blocks (5.00%) reserved for the super user
第一个数据块=0
Maximum filesystem blocks=4294967296
160 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
4096000
正在写入inode表: 完成
Writing superblocks and filesystem accounting information: 完成
This filesystem will be automatically checked every 25 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
第四步：挂载硬盘和MBR扇区备份
[root@localhost ~]# mount /dev/sdb1 /shiyan/
[root@localhost ~]# dd if=/dev/sda of=/shiyan/sda.mbr bs=512 count=1记录了1+0 的读入
记录了1+0 的写出
512字节(512 B)已复制，0.0246777 秒，20.7 kB/秒
第五步;破坏系统硬盘扇区和恢复系统
[root@localhost ~]# ls /shiyan/ #查看备份是否成功
lost+found sda.mbr
[root@localhost ~]# dd if=/dev/zero of=/dev/sda bs=512 count=1 #已经破坏/dev/sda系统盘
记录了1+0 的读入
记录了1+0 的写出
512字节(512 B)已复制，0.000240867 秒，2.1 MB/秒
来测试以下是否成功破坏
[root@localhost ~]# reboot #重启以下系统
如执行结果以下图片结果一样说明：系统盘已经丢失文件需要修复才可以进入系统
MBR扇区故障
请插入安装程序光盘到服务器里或者使用外部光驱启动，从光盘引导进入安全模式。
选择第三项“Rescue installed systen”
引导程序菜单
选择语言：默认英语 点击：OK
引导程序选择语言
选择键盘;美式键盘 点击:OK
选择键盘
是否开启网络访问：选择NO
是否开启网络访问
选择：Continue
引导程序菜单里面选项
选择：OK
选项OK
选择shell
shell选项界面
在shell界面将/dev/sdb1挂载使用，将里面的备份写入/dev/sda，重启
创建目录挂载备份
重启进入系统，MBR分区修复成功。
进入系统说明已经成功恢复
系统启动自检界面