.什么是MBR,MBR如何恢复损坏?
linux主机启动启动,将加载MBR启动引导程序,MBR硬盘0磁道0柱面1扇区前446字节存储在启动引导程序中,1扇区后64字节存储分区表,后面有两个字节,分区表的结尾标志符55AA
1)模拟MBR损坏引导程序:删除MBR引导程序文件
[root@lixiang grub]# rm grub.conf
rm: remove regular file `grub.conf'? y
2)重启系统reboot,这时,我们看到下面的图片出现在系统中
3)首先可以用find (hd0,0)/后接tab按键
4)输入root (hd0,0),出现下图:
5)输入kernel /vmlinuz-2.6.32-504.el6.x86_64 ro root=/dev/sda1 rhgb quiet,或者输入kernel /vmlinuz-2.6.32-504.el6.x86_64 ro root=LABEL=/ rhgb quiet (本法通用)【 注意我的是Centos6.6版本,你可以从其他地方复制,在这个地方/boot/grub/grub.conf,我先记录了这个内容。 ro root=UUID=2acb0807-4ecd-4305-a2e9-28446b3d85ca rd_NO_LUKS rd_NO_LVM.UTF-8;但是忘记也没关系。我会交另一种恢复的方法
6)输入initrd /initramfs-2.6.32-504.el6.x86_64.img
7)最后一步boot重启,当下面的奇迹发生时,系统将成功启动。但只是这次成功登录,下次登录还是会出现这个问题,所以我会备份的grub.conf.bak更改为grub.conf
MBR恢复方法二:
具体恢复方法如下:
1)选择加载光盘启动启动启动,选择救援模式
2)选择默认
3)选择OK
4)网络选择NO
5)选择continue
6)默认ok
7)选择shell Start shell,选择Ok
8)执行命令chroot /mnt/sysimage
9)下面执行mv /boot/grub/grub.conf.bak /boot/grub/grub.conf
10)设置本地硬盘启动,重新启动系统即可。
6.如果磁盘容量小于2T可以使用fdisk如果大于2,挂载T使用parted挂载
1)让我们做一下,比如/dev/sdb磁盘分为两个区域,1P 1L
[root@GW ~]# fdisk /dev/sdb 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): m Command action a toggle a bootable flag b edit bsd disklabel c toggle the dos compatibility flag d delete a partition l list known partition types m print this menu n add a new partition o create a new empty DOS partition table p print the partition table q quit without saving changes s create a new empty Sun disklabel t change a partition's system id u change display/entry units v verify the partition table w write table to disk and exit x extra functionality (experts only) Command (m for help): n Command action e extended p primary partition (1-4) p Partition number (1-4): 1 First cylinder (1-102, default 1): Using default value 1 Last cylinder, cylinders or size{K,M,G}(1-102, default 102): 20MB Command (m for help): n Command action e extended p primary partition (1-4) e Partition number (1-4): 2 First cylinder (21-102, default 21): Using default value 21 Last cylinder, cylinders or size{K,M,G}(21-102, default 102): Using default value 102 Command (m for help): p Disk /dev/sdb: 106 MB, 106954752 bytes 64 heads, 32 sectors/track, 102 cylinders Units = cylinders of 2048 * 512 = 1048576 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000602e5 Device Boot Start End Blocks Id System /dev/sdb1 1 20 20464 83 Linux /dev/sdb2 21 102 83968 5 Extended Command (m for help): n Command action l logical (5 or 电脑 over) p primary partition (1-4) l First cylinder (21-102, default 21): Using default value 21 Last cylinder, cylinders or size{K,M,G}(21-102, default 102): Using default value 102 Command (m for help): p Disk /dev/sdb: 106 MB, 106954752 bytes 64 heads, 32 sectors/track, 102 cylinders Units = cylinders of 2048 * 512 = 1048576 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000602e5 Device Boot Start End Blocks Id System /dev/sdb1 1 20 20464 83 Linux /dev/sdb2 21 102 83968 5 Extended /dev/sdb5 21 102 83952 83 Linux 分区完成后,我们可以用mkfs -t ext4 格式化分区 [root@GW ~]# mkfs -t ext4 /dev/sdb1 挂载分区,将sdb1挂载到/tmp目录下 [root@GW ~]# mount /dev/sdb1 /tmp 将文件挂载文件写入启动自启动 UUID=2acb0807-4电脑ecd-4305-a2e9-28446b3d85ca / ext4 defaults 1 1 UUID=edab26eb-e5da-47e2-914b-40f4bdf8347d /boot ext4 defaults 1 2 UUID=ff7ab69d-bdc2-40cd-816f-8c30a3e76737 swap swap defaults 0 0 tmpfs /dev/shm tmpfs defaults 0 0 devpts /dev/pts devpts gid=5,mode=620 0 0 sysfs /sys sysfs defaults 0 0 proc /proc proc defaults 0 0 /dev/sdb1 /tmp ext4 defaults 0 0 ~ "/etc/fstab" 16L, 841C written [root@GW ~]# mount -a #检查挂载是否有问题 [root@GW ~]# tune2fs -c -1 /dev/sdb1 tune2fs是调整和检查ext2/ext文件系统参数3,Windows如果下面发生意外断电死机,系统自检通常发生在下一次卡机中。Linux系统下还有文件系统自检,可以通过tune2fs自定义自检周期和方法 |
现在我们正在模拟硬盘parted分区
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