引導加載程序grub的使用詳解

為運行于虛擬機上的CentOS 6添加一個新硬件，提供兩個主分區

為硬盤建兩個主分區；并為其安裝grub
為硬盤的第一個主分區提供內核和ramdisk文件；為第二個分區提供rootfs
為rootfs提供bash、ls、cat程序以及所依賴的庫文件
為grub提供配置文件

將新的硬盤設置為第一啟動項并能夠正常啟動目標主機

1.新建分區

  [root@slave1 ~]# 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 0xf614f379.
   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)
   1
   Invalid partition number for type `1'
   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): +5G

   Command (m for help): n
   Command action
      e   extended
      p   primary partition (1-4)
   p
   Partition number (1-4): 2
   First cylinder (655-2610, default 655):
   Using default value 655
   Last cylinder, +cylinders or +size{K,M,G} (655-2610, default 2610): +5G

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

   Calling ioctl() to re-read partition table.
   Syncing disks.
   [root@slave1 ~]# 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: 0x00026a25

      Device Boot      Start         End      Blocks   Id  System
   /dev/sda1   *           1          64      512000   83  Linux
   Partition 1 does not end on cylinder boundary.
   /dev/sda2              64        2611    20458496   8e  Linux LVM

   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: 0xf614f379

      Device Boot      Start         End      Blocks   Id  System
   /dev/sdb1               1         654     5253223+  83  Linux
   /dev/sdb2             655        1308     5253255   83  Linux

   Disk /dev/mapper/vg_slave1-lv_root: 18.9 GB, 18865979392 bytes
   255 heads, 63 sectors/track, 2293 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

   Disk /dev/mapper/vg_slave1-lv_swap: 2080 MB, 2080374784 bytes
   255 heads, 63 sectors/track, 252 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

2.掛載boot和根文件系統

   [root@slave1 ~]# mke2fs -t ext4 /dev/sdb1
   [root@slave1 ~]# mke2fs -t ext4 /dev/sdb2
   [root@slave1 ~]# mkdir /myroot
   [root@slave1 ~]# mkdir /myroot/boot
   [root@slave1 ~]# mount /dev/sdb2 /myroot/boot
   [root@slave1 ~]# mkdir /myroot/sysroot
   [root@slave1 ~]# mount /dev/sdb1 /myroot/sysroot
   [root@slave1 myroot]# vi /etc/fstab
   /dev/sdb1               /myroot/sysroot                ext4     defaults        1 1
   /dev/sdb2               /myroot/boot           ext4     defaults        1 2

3.安裝配置grub

   [root@slave1 /]# grub-install --root-directory=/myroot /dev/sdb
   [root@slave1 boot]# cp /boot/vmlinuz-2.6.32-431.el6.x86_64 /myroot/boot/
   [root@slave1 boot]# cp /boot/initramfs-2.6.32-431.el6.x86_64.img /myroot/boot/
   [root@slave1 grub]# vim /myroot/boot/grub/grub.conf
    default=0
    timeout=5
    title centos6.5 simple
       root (hd1,1)
       kernel /vmlinuz-2.6.32-431.el6.x86_64 ro root=/dev/sdb1 selinux=0 init=/bin/bash
       initrd /initramfs-2.6.32-431.el6.x86_64.img

4.創建根文件系統

   [root@slave1 myroot]# mkdir etc bin sbin lib lib64 usr home root sys proc var mnt media
   [root@slave1 myroot]# cp /bin/{bash,ls,cat} /myroot/bin/
   [root@slave1 bin]# ldd bash
           linux-vdso.so.1 =>  (0x00007fffc5f45000)
           libtinfo.so.5 => /lib64/libtinfo.so.5 (0x00007f0fbe3f8000)
           libdl.so.2 => /lib64/libdl.so.2 (0x00007f0fbe1f4000)
           libc.so.6 => /lib64/libc.so.6 (0x00007f0fbde5f000)
           /lib64/ld-linux-x86-64.so.2 (0x00007f0fbe622000)
   [root@slave1 bin]# cp  /lib64/{libtinfo.so.5,libdl.so.2,libc.so.6,ld-linux-x86-64.so.2}  /myroot/lib64/
   [root@slave1 bin]# ldd ls
           linux-vdso.so.1 =>  (0x00007fff6adfe000)
           libselinux.so.1 => /lib64/libselinux.so.1 (0x00007fd0f7832000)
           librt.so.1 => /lib64/librt.so.1 (0x00007fd0f762a000)
           libcap.so.2 => /lib64/libcap.so.2 (0x00007fd0f7425000)
           libacl.so.1 => /lib64/libacl.so.1 (0x00007fd0f721d000)
           libc.so.6 => /lib64/libc.so.6 (0x00007fd0f6e89000)
           libdl.so.2 => /lib64/libdl.so.2 (0x00007fd0f6c84000)
           /lib64/ld-linux-x86-64.so.2 (0x00007fd0f7a5a000)
           libpthread.so.0 => /lib64/libpthread.so.0 (0x00007fd0f6a67000)
           libattr.so.1 => /lib64/libattr.so.1 (0x00007fd0f6862000)
   [root@slave1 bin]# cp /lib64/ {libselinux.so.1,librt.so.1,libcap.so.2,libacl.so.1,libc.so.6,libdl.so.2,ld-linux-x86-64.so.2,libpthread.so.0,libattr.so.1} /myroot/lib64/   
     cp: overwrite `/myroot/lib64/libc.so.6'? no
     cp: overwrite `/myroot/lib64/libdl.so.2'? no
     cp: overwrite `/myroot/lib64/ld-linux-x86-64.so.2'? no
   [root@slave1 bin]# ldd cat
           linux-vdso.so.1 =>  (0x00007fff749e7000)
           libc.so.6 => /lib64/libc.so.6 (0x00007f6bdc516000)
           /lib64/ld-linux-x86-64.so.2 (0x00007f6bdc8b3000)
   [root@slave1 bin]# cp  /lib64/{libc.so.6,ld-linux-x86-64.so.2} /myroot/lib64/
     cp: overwrite `/myroot/lib64/libc.so.6'? no
     cp: overwrite `/myroot/lib64/ld-linux-x86-64.so.2'? no