1.远程备份恢复
以centos6为例 先备份为mbr文件 拷贝到centos7 主机中（172.18.254.154）
[[email protected] ~]#dd if=/dev/sda of=mbr bs=1 count=512
[[email protected] ~]#scp mbr 172.18.254.154:/app/
* scp 远程主机与当前主机互传文件
命令格式：scp local_file [email protected]_ip:remote_folder
scp /home/daisy/full.tar.gz [email protected]:/home/root
从远程复制到本地，只要将从本地复制到远程的命令的 后2个参数 调换顺序 即可；
scp [email protected]:/home/root/others/music /home/space/music/1.mp3
[[email protected] ~]# scp /etc/yum.repos.d/cdrom.repo [email protected]:/test
Are you sure you want to continue connecting (yes/no)? 输入yes或者no 不是y 或者n
[email protected]'s password: 登录密码
对centos6中磁盘清空bmr扇区 (分区表为0 计算机引导启动失效) 关机后系统已无法重新启动
[[email protected] ~]#dd if=/dev/zero of=/dev/sda bs=1 count=512
512+0 records in
512+0 records out
512 bytes (512 B) copied, 0.000730352 s, 701 kB/s
[[email protected] ~]#fdisk -l /dev/sda
Disk /dev/sda: 214.7 GB, 214748364800 bytes
255 heads, 63 sectors/track, 26108 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
记住磁盘文件名并移除
在centos7中 新加磁盘选取文件名 相当于centos6中拔出磁盘 重新插在centos7主机上
生成磁盘为sdc 将mbr恢复到sdc中
[[email protected] app]$dd if=mbr of=/dev/sdc
移除sdc 在centos6中重新添加磁盘文件名为centOS 64 位-000005.vmdk
启动centos6恢复正常
2.当前主机硬盘恢复
适合当前主机磁盘数据发生更改 恢复到某一时期 分区磁盘sda未被破坏
[[email protected] test]#dd if=/dev/sda of=/dev/sdm bs=1 count=66 skip=446 seek=446
[[email protected] app]$dd if=/dev/sda of=/dev/sdn sdn分区大小大于sda分区大小
[[email protected] ~]#dd if=/dev/sda of=mbr bs=1 count=512