Centos修复boot分区

- 日理万妓 2023-06-27 08:42 67阅读 0赞

# 1，对比boot分区: 完整的/损坏的 #

[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