linux不重启挂载磁盘安装grub

挂载、分区、grub

通过给一块新磁盘安装grub回顾磁盘挂载、分区文件系统创建等操作：

该实验基于（CtonOS6.8；kernel:2.6.32-642.15.1.el6.x86_64）

1.通过VMware Workstationg添加一块磁盘（SCSI）；

2./sys下SCSI扫描，查看主机总线号，磁盘肯定是有总线连接着：

 [root@cl Test]# ls /sys/class/scsi_host/
 host0  host1  host2
 [root@cl Test]# echo "- - -" >  /sys/class/scsi_host/host0/scan
 [root@cl Test]# echo "- - -" >  /sys/class/scsi_host/host1/scan
 [root@cl Test]# echo "- - -" >  /sys/class/scsi_host/host2/scan
 [root@cl Test]# fdisk -l

3.创建分区：

 [root@cl Test]# 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 0xa61749e4.
 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  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 (-)
 p
 Partition number (-):
 First cylinder (-, default ):
 Using default value
 Last cylinder, +cylinders or +size{K,M,G} (-, default ): +200M

 Command (m for help): n
 Command action
    e   extended
    p   primary partition (-)
 p
 Partition number (-):
 First cylinder (-, default ):
 Using default value
 Last cylinder, +cylinders or +size{K,M,G} (-, default ): +2G

 Command (m for help): t
 Partition number (-):
 Hex code (type L to list codes):
 Changed system type of partition  to  (Linux swap / Solaris)

 Command (m for help): n
 Command action
    e   extended
    p   primary partition (-)
 p
 Partition number (-):
 First cylinder (-, default ):
 Using default value
 Last cylinder, +cylinders or +size{K,M,G} (-, default ): +5G

 Command (m for help): w
 The partition table has been altered!

 Calling ioctl() to re-read partition table.
 Syncing disks.
 [root@cl Test]# partx -a /dev/sdb
 BLKPG: Device or resource busy
 error adding partition
 BLKPG: Device or resource busy
 error adding partition
 BLKPG: Device or resource busy
 error adding partition
 [root@cl Test]# cat /proc/partitions
 major minor  #blocks  name

               sda
                  sda1
                 sda2
                 sda3
                       sda4
                sda5
                 sda6
                 sda7
               sdb
                 sdb1
                sdb2
                sdb3

4.创建文件系统：

 [root@cl Test]# mke2fs -t ext4 /dev/sdb1
 [root@cl Test]# mke2fs -t ext4 /dev/sdb3
 [root@cl Test]# mkswap /dev/sdb2

5.挂载分区：

 [root@cl ~]# mkdir /mnt/boot
 [root@cl ~]# mount /dev/sdb1 /mnt/boot/
 [root@cl ~]# ls /mnt/boot/
 lost+found

6.安装grub：

 [root@cl ~]# grub-install --root-directory=/mnt /dev/sdb1 （指明/的位置在mnt下）
 Probing devices to guess BIOS drives. This may take a long time.
 Installation finished. No error reported.
 This is the contents of the device map /mnt/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'.

 (fd0)    /dev/fd0
 (hd0)    /dev/sda
 (hd1)    /dev/sdb
 [root@cl ~]# ls /mnt/boot/
 grub  lost+found
 [root@cl ~]# ls /mnt/boot/grub/
 device.map     ffs_stage1_5      minix_stage1_5     stage2           xfs_stage1_5
 e2fs_stage1_5  iso9660_stage1_5  reiserfs_stage1_5  ufs2_stage1_5
 fat_stage1_5   jfs_stage1_5      stage1             vstafs_stage1_5

7.配置grub：

 [root@cl ~]# cp /boot/vmlinuz-2.6.-.el6.x86_64 /mnt/boot/vmlinuz
 [root@cl ~]# cp /boot/initramfs-2.6.-.el6.x86_64.img /mnt/boot/initramfs.img
 [root@cl ~]# vim /mnt/boot/grub/grub.conf

default=0
timeout=5
title CentOS (Express)
root (hd0,0)
kernel /vmlinuz ro root=/dev/sda3
initrd /initramfs.img

8.创建根文件目录：

 [root@cl ~]# mkdir /mnt/sysroot
 [root@cl ~]# mount /dev/sdb3 /mnt/sysroot/
 [root@cl ~]# cd /mnt/sysroot/
 [root@cl sysroot]# mkdir -p etc bin sbin lib lib64 dev proc sys tmp var usr home mnt media
 [root@cl sysroot]# ls
 bin  dev  etc  home  lib  lib64  lost+found  media  mnt  proc  sbin  sys  tmp  usr  var
 [root@cl sysroot]# cp /bin/bash /mnt/sysroot/bin/ （复制程序bash）
 [root@cl sysroot]# ldd /bin/bash (查看程序依赖库文件)
     linux-vdso.so. =>  (0x00007fffd39f9000)
     libtinfo.so. => /lib64/libtinfo.so. (0x0000003cc3800000)
     libdl.so. => /lib64/libdl.so. (0x0000003cc1c00000)
     libc.so. => /lib64/libc.so. (0x0000003cc2000000)
     /lib64/ld-linux-x86-.so. (0x0000003cc1800000)
 [root@cl sysroot]# cp /lib64/libtinfo.so. /mnt/sysroot/lib64/
 [root@cl sysroot]# cp /lib64/libdl.so. /mnt/sysroot/lib64/
 [root@cl sysroot]# cp /lib64/libc.so. /mnt/sysroot/lib64/
 [root@cl sysroot]# cp /lib64/ld-linux-x86-.so. /mnt/sysroot/lib64/
 [root@cl sysroot]# cd
 [root@cl ~]# chroot /mnt/sysroot/ （切换根）
 bash-4.1#
 bash-4.1# exit
 exit

9.编辑启动init为/bin/bash：

[root@cl ~]# vim /mnt/boot/grub/grub.conf 

default=
timeout=
title CentOS (Express)
         root (hd0,)
         kernel /vmlinuz ro root=/dev/sda3 init=/bin/bash
         initrd /initramfs.img
[root@cl ~]# sync

note：该操作把bash当做第一个用户空间运行进程启动；

note：sync命令的作用是，将有关文件系统的存储器常驻信息送入物理介质内。在暂停系统之前，比如要重新启动机器，一定要去执行sync命令。

补充：模拟破坏和修复方法一：

 [root@cl ~]# dd if=/dev/sda of=/root/mbr.bak count= bs=
 + records in
 + records out
  bytes ( B) copied, 0.000155983 s, 3.3 MB/
 [root@cl ~]# dd if=/dev/zero of=/dev/sda bs= count=
 + records in
 + records out
  bytes ( B) copied, 0.000307597 s,  kB/s
 [root@cl ~]# sync
 [root@cl ~]# 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

　　　　模拟破坏和修复方法二：

 [root@cl ~]# dd if=/dev/zero of=/dev/sda bs= count=
 + records in
 + records out
  bytes ( B) copied, 0.0170366 s, 11.7 kB/s
 [root@cl ~]# sync
 [root@cl ~]# 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,)
 root (hd0,)
  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)"...   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@cl ~]# sync

　　　　模拟破坏和修复方法三：（重启后救援模式修复）

重启：

[root@cl ~]# dd if=/dev/zero of=/dev/sda bs= count=
+ records in
+ records out
 bytes ( B) copied, 0.000283877 s,  kB/s
[root@cl ~]# sync
[root@cl ~]# reboot

Broadcast message from root@cl.y.dba
    (/dev/pts/) at : ...

The system is going down for reboot NOW!

修复：1.选择镜像光盘：

　　2.重启系统选择救援模式：

　　3.进入shell：

4.修复并重启：