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MBR

概念理解

MBR - Master Boot Record 主引导记录,也有人称之为主引导扇区

硬盘的最前面的512字节,包含两部分

  • 446字节的'引导代码'
  • 4个16字节的'磁盘分区表(Disk Partition Tabl)'
  • 2个字节的结束标志

查看

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root@jp-vps:~$dd if=/dev/vda bs=512 count=1 | hexdump -C
1+0 records in
1+0 records out
512 bytes copied, 0.000414571 s, 1.2 MB/s
00000000 eb 63 90 10 8e d0 bc 00 b0 b8 00 00 8e d8 8e c0 |.c..............|
00000010 fb be 00 7c bf 00 06 b9 00 02 f3 a4 ea 21 06 00 |...|.........!..|
00000020 00 be be 07 38 04 75 0b 83 c6 10 81 fe fe 07 75 |....8.u........u|
00000030 f3 eb 16 b4 02 b0 01 bb 00 7c b2 80 8a 74 01 8b |.........|...t..|
00000040 4c 02 cd 13 ea 00 7c 00 00 eb fe 00 00 00 00 00 |L.....|.........|
00000050 00 00 00 00 00 00 00 00 00 00 00 80 01 00 00 00 |................|
00000060 00 00 00 00 ff fa 90 90 f6 c2 80 74 05 f6 c2 70 |...........t...p|
00000070 74 02 b2 80 ea 79 7c 00 00 31 c0 8e d8 8e d0 bc |t....y|..1......|
00000080 00 20 fb a0 64 7c 3c ff 74 02 88 c2 52 bb 17 04 |. ..d|<.t...R...|
00000090 f6 07 03 74 06 be 88 7d e8 17 01 be 05 7c b4 41 |...t...}.....|.A|
000000a0 bb aa 55 cd 13 5a 52 72 3d 81 fb 55 aa 75 37 83 |..U..ZRr=..U.u7.|
000000b0 e1 01 74 32 31 c0 89 44 04 40 88 44 ff 89 44 02 |..t21..D.@.D..D.|
000000c0 c7 04 10 00 66 8b 1e 5c 7c 66 89 5c 08 66 8b 1e |....f..\|f.\.f..|
000000d0 60 7c 66 89 5c 0c c7 44 06 00 70 b4 42 cd 13 72 |`|f.\..D..p.B..r|
000000e0 05 bb 00 70 eb 76 b4 08 cd 13 73 0d 5a 84 d2 0f |...p.v....s.Z...|
000000f0 83 d0 00 be 93 7d e9 82 00 66 0f b6 c6 88 64 ff |.....}...f....d.|
00000100 40 66 89 44 04 0f b6 d1 c1 e2 02 88 e8 88 f4 40 |@f.D...........@|
00000110 89 44 08 0f b6 c2 c0 e8 02 66 89 04 66 a1 60 7c |.D.......f..f.`||
00000120 66 09 c0 75 4e 66 a1 5c 7c 66 31 d2 66 f7 34 88 |f..uNf.\|f1.f.4.|
00000130 d1 31 d2 66 f7 74 04 3b 44 08 7d 37 fe c1 88 c5 |.1.f.t.;D.}7....|
00000140 30 c0 c1 e8 02 08 c1 88 d0 5a 88 c6 bb 00 70 8e |0........Z....p.|
00000150 c3 31 db b8 01 02 cd 13 72 1e 8c c3 60 1e b9 00 |.1......r...`...|
00000160 01 8e db 31 f6 bf 00 80 8e c6 fc f3 a5 1f 61 ff |...1..........a.|
00000170 26 5a 7c be 8e 7d eb 03 be 9d 7d e8 34 00 be a2 |&Z|..}....}.4...|
00000180 7d e8 2e 00 cd 18 eb fe 47 52 55 42 20 00 47 65 |}.......GRUB .Ge|
00000190 6f 6d 00 48 61 72 64 20 44 69 73 6b 00 52 65 61 |om.Hard Disk.Rea|
000001a0 64 00 20 45 72 72 6f 72 0d 0a 00 bb 01 00 b4 0e |d. Error........|
000001b0 cd 10 ac 3c 00 75 f4 c3 3b 7f af 02 00 00 80 20 |...<.u..;...... |
000001c0 21 00 83 fe ff ff 00 08 00 00 df f7 1f 03 00 00 |!...............|
000001d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
*
000001f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 55 aa |..............U.|
00000200

用途

机器开机后读取硬盘时必须要读取的第一个扇区;

引导代码(程序) 加载boot loader

备份/恢复分区表

备份

1
root@jp-vps:~$dd if=/dev/vda of=test bs=512 count=1

恢复

1
root@jp-vps:~$dd if=test of=/dev/vda bs=1 skip=446 count=66