[root@localhost ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sr0 11:0 1 1024M 0 rom
sda 8:0 0 48G 0 disk
├─sda1 8:1 0 200M 0 part /boot
├─sda2 8:2 0 5G 0 part /
└─sda3 8:3 0 1G 0 part [SWAP]
sdb 8:16 0 28G 0 disk
├─sdb1 8:17 0 305.9M 0 part
├─sdb2 8:18 0 25G 0 part
└─sdb3 8:19 0 2.7G 0 part
#1,查看完整的boot分区数据[root@localhost ~]# dd if=/dev/sda of=mr.bak count=1 bs=512
1+0 records in
1+0 records out
512 bytes (512 B) copied, 0.000209593 s, 2.4 MB/s
[root@localhost ~]# sync[root@localhost ~]# file mr.bak
mr.bak: x86 boot sector; GRand Unified Bootloader, stage1 version 0x3, boot drive 0x80, 1st sector stage2 0x62bc, GRUB version 0.94; partition 1: ID=0x83, active, starthead 32, startsector 2048, 409600 sectors; partition 2: ID=0x83, starthead 159, startsector 411648, 10485760 sectors; partition 3: ID=0x82, starthead 84, startsector 10897408, 2097152 sectors, code offset 0x48
#2,查看损坏的boot分区数据[root@localhost ~]# dd if=/dev/zero of=/dev/sda count=1 bs=300
1+0 records in
1+0 records out
300 bytes (300 B) copied, 0.00140651 s, 213 kB/s
[root@localhost ~]# sync[root@localhost ~]# dd if=/dev/sda of=mr.bak.break count=1 bs=512
1+0 records in
1+0 records out
512 bytes (512 B) copied, 0.000219264 s, 2.3 MB/s
[root@localhost ~]# file mr.bak.break
mr.bak.break: x86 boot sector; partition 1: ID=0x83, active, starthead 32, startsector 2048, 409600 sectors; partition 2: ID=0x83, starthead 159, startsector 411648, 10485760 sectors; partition 3: ID=0x82, starthead 84, startsector 10897408, 2097152 sectors, code offset 0x0
2, 修复boot分区
2.1 , 系统还能运行时: grub-install 修复
# grub-install 修复损坏的boot分区[root@localhost ~]# grub-install --root-directory=/ /dev/sda
Installation finished. No error reported.
This is the contents of the device map //boot/grub/device.map.
Check if this is correct or not. If any of the lines is incorrect,
fix it and re-run the script `grub-install'.
# this device map was generated by anaconda(hd0) /dev/sda
[root@localhost ~]# [root@localhost ~]# [root@localhost ~]# [root@localhost ~]# dd if=/dev/zero of=/dev/sda count=1 bs=200
1+0 records in
1+0 records out
200 bytes (200 B) copied, 0.000935312 s, 214 kB/s
2.2 , 系统不能运行时: grub命令行 修复
# grub命令行 修复损坏的boot分区[root@localhost ~]# grub
Probing devices to guess BIOS drives. This may take a long time.
GNU GRUB version 0.97 (640K lower / 3072K upper memory)[ Minimal BASH-like line editing is supported. For the first word, TAB
lists possible command completions. Anywhere else TAB lists the possible
completions of a device/filename.]
grub> root (hd0,0)
root (hd0,0)
Filesystem type is ext2fs, partition type 0x83
grub> setup (hd0)
setup (hd0)
Checking if"/boot/grub/stage1" exists... no
Checking if"/grub/stage1" exists... yes
Checking if"/grub/stage2" exists... yes
Checking if"/grub/e2fs_stage1_5" exists... yes
Running "embed /grub/e2fs_stage1_5 (hd0)"... 27 sectors are embedded.
succeeded
Running "install /grub/stage1 (hd0) (hd0)1+27 p (hd0,0)/grub/stage2 /grub/grub.conf"... succeeded
Done.
grub> quit
quit
[root@localhost ~]# sync
