linux修复丢失的分区表
先模拟破快分区表
dd if=/dev/zero of=/dev/vdb bs=512 count=1
然后先使用 parted尝试修复
parted /dev/vdb
GNU Parted 2.1
使用 /dev/vdb
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) rescue
错误: /dev/vdb: unrecognised disk label
猜是MSDOS的于是 (parted) mklabel msdos
然后再rescue
(parted) rescue
起始点？ 0
结束点？ 10000
没有原来分区表的信息，只能猜，没有任何收获，尝试使用gpart工具
gpart /dev/vdb
Begin scan...
Possible extended partition at offset(601mb)
Possible partition(Linux ext2), size(4518mb), offset(601mb)
End scan.
Checking partitions...
Partition(Linux ext2 filesystem): primary
Ok.
Guessed primary partition table:
Primary partition(1)
type: 131(0x83)(Linux ext2 filesystem)
size: 4518mb #s(9253376) s(1231839-10485214)
chs: (1023/15/63)-(1023/15/63)d (1222/1/1)-(10401/15/62)r
Primary partition(2)
type: 000(0x00)(unused)
size: 0mb #s(0) s(0-0)
chs: (0/0/0)-(0/0/0)d (0/0/0)-(0/0/0)r
Primary partition(3)
type: 000(0x00)(unused)
size: 0mb #s(0) s(0-0)
chs: (0/0/0)-(0/0/0)d (0/0/0)-(0/0/0)r
Primary partition(4)
type: 000(0x00)(unused)
size: 0mb #s(0) s(0-0)
chs: (0/0/0)-(0/0/0)d (0/0/0)-(0/0/0)r
有一点收获，于是将猜的结果写入磁盘
root@localhost ~]# gpart -W /dev/vdb /dev/vdb
Begin scan... （时间很长)
1 - Absolute start sector ( 0)
2 - Absolute sector count ( 0)
3 - Partition type ( 0)(unused)
这里会让你填三个值，第一个，第二个，我怎么可能能记得！选第三个，由于记得有一个拓展分区，就写了Extended
Disk /dev/vdb: 5368 MB, 5368709120 bytes
16 heads, 63 sectors/track, 10402 cylinders
Units = cylinders of 1008 * 512 = 516096 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000d0da8
Device Boot Start End Blocks Id System
/dev/vdb1 1223 10402 4626688 83 Linux
/dev/vdb4 * 1 1 0 0 Empty
结果找回来一个分区，注意vdb1,挂载起来，发现数据回来了，晕。
网上的testdisk，貌似认不到虚拟机的硬盘，晕
最后尝试 fsck一下，看行不行
结果依然不行，判他死缓，告诉大家，备份非常重要，不要抱着侥幸心里过关!
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补充一下，后来发现其实 gpart 很好用，之前不行，是因为磁盘vdb没有分区和数据，后来我把vdb分了4个区，都有数据，执行gpart，很快就修复了
[root@localhost ~]# gpart /dev/vdb
Begin scan...
Possible partition(Linux ext2), size(100mb), offset(0mb)
Possible partition(Linux ext2), size(200mb), offset(100mb)
Possible partition(Linux ext2), size(300mb), offset(300mb)
Possible extended partition at offset(601mb)
Possible partition(Linux ext2), size(4518mb), offset(601mb)
End scan.
Checking partitions...
Partition(Linux ext2 filesystem): primary
Partition(Linux ext2 filesystem): primary
Partition(Linux ext2 filesystem): primary
Partition(Linux ext2 filesystem): primary
Ok.
Guessed primary partition table:
Primary partition(1)
type: 131(0x83)(Linux ext2 filesystem)
size: 100mb #s(205568) s(63-205630)
chs: (0/1/1)-(203/15/62)d (0/1/1)-(203/15/62)r
Primary partition(2)
type: 131(0x83)(Linux ext2 filesystem)
size: 200mb #s(409602) s(205632-615233)
chs: (204/0/1)-(610/5/39)d (204/0/1)-(610/5/39)r
Primary partition(3)
type: 131(0x83)(Linux ext2 filesystem)
size: 300mb #s(615888) s(615888-1231775)
chs: (611/0/1)-(1023/15/63)d (611/0/1)-(1221/15/63)r
Primary partition(4)
type: 131(0x83)(Linux ext2 filesystem)
size: 4518mb #s(9253376) s(1231839-10485214)
chs: (1023/15/63)-(1023/15/63)d (1222/1/1)-(10401/15/62)r
[root@localhost ~]# gpart -W /dev/vdb /dev/vdb
Begin scan...
Possible partition(Linux ext2), size(100mb), offset(0mb)
Possible partition(Linux ext2), size(200mb), offset(100mb)
Possible partition(Linux ext2), size(300mb), offset(300mb)
Possible extended partition at offset(601mb)
Possible partition(Linux ext2), size(4518mb), offset(601mb)
End scan.
Checking partitions...
Partition(Linux ext2 filesystem): primary
Partition(Linux ext2 filesystem): primary
Partition(Linux ext2 filesystem): primary
Partition(Linux ext2 filesystem): primary
Ok.
Guessed primary partition table:
Primary partition(1)
type: 131(0x83)(Linux ext2 filesystem)
size: 100mb #s(205568) s(63-205630)
chs: (0/1/1)-(203/15/62)d (0/1/1)-(203/15/62)r
Primary partition(2)
type: 131(0x83)(Linux ext2 filesystem)
size: 200mb #s(409602) s(205632-615233)
chs: (204/0/1)-(610/5/39)d (204/0/1)-(610/5/39)r
Primary partition(3)
type: 131(0x83)(Linux ext2 filesystem)
size: 300mb #s(615888) s(615888-1231775)
chs: (611/0/1)-(1023/15/63)d (611/0/1)-(1221/15/63)r
Primary partition(4)
type: 131(0x83)(Linux ext2 filesystem)
size: 4518mb #s(9253376) s(1231839-10485214)
chs: (1023/15/63)-(1023/15/63)d (1222/1/1)-(10401/15/62)r
Edit this table (y,n) : n
Activate which partition (1..4, q to quit) : 1234
Activate which partition (1..4, q to quit) : 1..4
Write this partition table (y,n) : y
Warning: partition table written, you should reboot now.
[root@localhost ~]# fdisk -l
Disk /dev/vda: 32.2 GB, 32212254720 bytes
16 heads, 63 sectors/track, 62415 cylinders
Units = cylinders of 1008 * 512 = 516096 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00014cd2
Device Boot Start End Blocks Id System
/dev/vda1 * 3 1018 512000 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/vda2 1018 5179 2097152 82 Linux swap / Solaris
Partition 2 does not end on cylinder boundary.
/dev/vda3 5179 62416 28847104 83 Linux
Partition 3 does not end on cylinder boundary.
Disk /dev/vdb: 5368 MB, 5368709120 bytes
16 heads, 63 sectors/track, 10402 cylinders
Units = cylinders of 1008 * 512 = 516096 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Device Boot Start End Blocks Id System
/dev/vdb1 * 1 204 102784 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/vdb2 205 611 204801 83 Linux
Partition 2 does not end on cylinder boundary.
/dev/vdb3 612 1222 307944 83 Linux
/dev/vdb4 1223 10402 4626688 83 Linux
[root@localhost ~]# mount /dev/vdb
vdb vdb1 vdb2 vdb3 vdb4
[root@localhost ~]# mount /dev/vdb1 /mnt/1/
[root@localhost ~]# mount /dev/vdb2 /mnt/2/
[root@localhost ~]# mount /dev/vdb3 /mnt/3/
[root@localhost ~]# mount /dev/vdb5 /mnt/4/
mount: you must specify the filesystem type
[root@localhost ~]# mount /dev/vdb4 /mnt/4/
[root@localhost ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/vda3 27G 6.0G 20G 24% /
tmpfs 4.0G 72K 4.0G 1% /dev/shm
/dev/vda1 477M 33M 419M 8% /boot
/dev/vdb1 98M 5.6M 87M 7% /mnt/1
/dev/vdb2 194M 5.6M 179M 4% /mnt/2
/dev/vdb3 292M 11M 267M 4% /mnt/3
/dev/vdb4 4.4G 137M 4.0G 4% /mnt/4