超级块：从磁盘上读出来的第一块信息就是超级块(superblock),它记录了磁盘的几何尺寸，可用空间容量最重要的是记录了第一个inode位置，就是”/ “，ext2/3文件存取都是通过inode定位的，比如使用/home/blue/test这个文件，首先先找到/的inode,然后找到 /home的inode,再找到blue的inode最后找到test的inode，可见没有超级块，文件系统就没有使用意义。来看看ext2/3文件系统的结构图：可以看出，ext2/3文件系统是由许多的块组组成，在其他的块组中保存了超级块的复本通常只有块组0的超级块会被程序读取，比如mount，e2fsck 默认就只读取块组0的。如果超级块被写上其他的数据，比如被mkswap后，超级块保存的信息就丢失了mount,fsck就会报告超级块损坏，无法正常挂载系统了，鉴于超级块如此重要，文件系统的设计者将这些超级块拷贝了许多份分散在整个文件系统的块组中。我们要做的就是用分散在其他块组中超级块替换已经损坏的，就万事大吉啦。首先找出超级块都被藏到哪去了 注意： -n 参数表示只列出文件系统的信息，并不真的格式化分区，使用mke2fs时一定要加倍小心不然真给格了一定要小心。 mke2fs -n /dev/hda10
mke2fs 1.35 (28-Feb-2004)Filesystem label=OS type: LinuxBlock size=4096 (log=2)Fragment size=4096 (log=2)883008 inodes, 1763125 blocks88156 blocks (5.00%) reserved for the super userFirst data block=054 block groups32768 blocks per group, 32768 fragments per group16352 inodes per groupSuperblock backups stored on blocks: 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632
原来藏在32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632下面就使用e2fsck命令修复。
e2fsck -b 32768 /dev/hda10 -b参数指定超级块位置，不使用默认的超级块，默认的都坏掉了。
按照提示，一路y后。
mount /dev/sde1 /foo
mount: wrong fs type, bad option, bad superblock on
/dev/sde1,
or too many mounted file
systems
的问题。请问这种问题怎么能解决呢？
回答：
这个错误信息标识 /dev/sde1 设备上的 ext3
文件系统的超级块损坏了，ext3 文件系统的元数据保存在超级块中。
ext3 文件系统还有一些备份的超级块，可以尝试用备份的超级块加载 ext3
文件系统和修复 ext3 文件系统。
备份的超级块信息可以通过以下命令获得，这个命令模拟 ext3
文件系统创建时的动作并打印出备份超级块的位置，给出的位置缺省是以4k为单位的，mount
在使用时需要为它提供以1k为单位的偏移，需要乘4：
注意!!!!!一定要使用\”-n\”作为参数模拟 ext3 文件系统的创建而不是真的创建 ext3
文件系统
# mkfs.ext3 -n /dev/hda7
mke2fs 1.38 (30-Jun-2005)
Filesystem
label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096
(log=2)
2198880 inodes, 4393738 blocks
219686 blocks (5.00%) reserved for
the super user
First data block=0
135 block groups
32768 blocks per
group, 32768 fragments per group
16288 inodes per group
Superblock backups
stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200,
884736, 1605632, 2654208,
4096000
使用备份的超级块来加载 ext3
文件系统的命令:
语法： mount.ext3 -o sb=n
#
mount.ext3 -o sb=131072 /dev/hda7 /media/hda7
使用备份的超级块来修复 ext3
文件系统的命令
语法：fsck.ext3 -b superblock
# fsck.ext3 -b 32768
/dev/hda7
—————————————–
1，一服务器/dev/sdb文件系统损坏，重启后系统启不来，进入单用户模式fsck无法修复，把/etc/fstab中的/dev/sdb注释掉后，系统成功起来。
2，mount挂载/dev/sdb提示bad superblock 错误，无法正常挂载：
[root@localhost ~]# mount /dev/sdb /test
mount: wrong fs type, bad option, bad superblock on /dev/sdb,
or too many mounted file systems
3，尝试直接指定备用超级块来挂载分区。通过mkfs -n可以查看到备份超级块的位置：
[root@localhost ~]# mkfs.ext3 -n /dev/sdb
mke2fs 1.35 (28-Feb-2004)
/dev/sdb is entire device, not just one partition!
Proceed anyway? (y,n) y
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
365854720 inodes, 731688960 blocks
36584448 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
22330 block groups
32768 blocks per group, 32768 fragments per group
16384 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968,
102400000, 214990848, 512000000, 550731776, 644972544
也可以通过dumpe2fs查看备份超级块的位置：
[root@localhost ~]# dumpe2fs /dev/sdb | grep –before-context=1 superblock
dumpe2fs 1.35 (28-Feb-2004)
Group 0: (Blocks 0-32767)
Primary superblock at 0, Group deｓｃｒｉｐｔors at 1-175
–
Group 1: (Blocks 32768-65535)
Backup superblock at 32768, Group deｓｃｒｉｐｔors at 32769-32943
–
Group 3: (Blocks 98304-131071)
Backup superblock at 98304, Group deｓｃｒｉｐｔors at 98305-98479
–
Group 5: (Blocks 163840-196607)
Backup superblock at 163840, Group deｓｃｒｉｐｔors at 163841-164015
–
Group 7: (Blocks 229376-262143)
Backup superblock at 229376, Group deｓｃｒｉｐｔors at 229377-229551
–
Group 9: (Blocks 294912-327679)
Backup superblock at 294912, Group deｓｃｒｉｐｔors at 294913-295087
–
Group 25: (Blocks 819200-851967)
Backup superblock at 819200, Group deｓｃｒｉｐｔors at 819201-819375
–
Group 27: (Blocks 884736-917503)
Backup superblock at 884736, Group deｓｃｒｉｐｔors at 884737-884911
–
Group 49: (Blocks 1605632-1638399)
Backup superblock at 1605632, Group deｓｃｒｉｐｔors at 1605633-1605807
–
Group 81: (Blocks 2654208-2686975)
Backup superblock at 2654208, Group deｓｃｒｉｐｔors at 2654209-2654383
–
Group 125: (Blocks 4096000-4128767)
Backup superblock at 4096000, Group deｓｃｒｉｐｔors at 4096001-4096175
–
Group 243: (Blocks 7962624-7995391)
Backup superblock at 7962624, Group deｓｃｒｉｐｔors at 7962625-7962799
4，用查看到的备份超级块来挂载/dev/sdb，也无法成功：
[root@localhost ~]# mount -o sb=32768 /dev/sdb /test
mount: wrong fs type, bad option, bad superblock on /dev/sdb,
or too many mounted file systems
分区情况如下：
[root@localhost ~]# fdisk -l
Disk /dev/sda: 998.9 GB, 998999326720 bytes
255 heads, 63 sectors/track, 121454 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sda1 * 1 16 128488+ 83 Linux
/dev/sda2 17 6390 51199155 83 Linux
/dev/sda3 6391 12764 51199155 83 Linux
/dev/sda4 12765 121454 873052425 5 Extended
/dev/sda5 12765 13796 8289508+ 82 Linux swap
/dev/sda6 13797 121454 864762853+ 83 Linux
Disk /dev/sdb: 2996.9 GB, 2996997980160 bytes
255 heads, 63 sectors/track, 364364 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk /dev/sdb doesn’t contain a valid partition table
[root@localhost ~]# parted /dev/sdb
GNU Parted 1.6.19
Copyright (C) 1998 – 2004 Free Software Foundation, Inc.
This program is free software, covered by the GNU General Public License.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
Using /dev/sdb
(parted) print
Disk geometry for /dev/sdb: 0.000-2858160.000 megabytes
Disk label type: loop
Minor Start End Filesystem Flags
1 0.000 2858160.000 ext3
(parted) quit
Information: Don’t forget to update /etc/fstab, if necessary.
5，尝试用备份超级块去fsck修复分区，报“illegal bitmap block”错误，也无法成功：
[root@localhost ~]# fsck.ext3 -b 32768 /dev/sdb
e2fsck 1.35 (28-Feb-2004)
Block bitmap for group 4992 is not in group. (block 809140608)
Relocate
Inode bitmap for group 4992 is not in group. (block 5385)
Relocate
Inode table for group 4992 is not in group. (block 1295485238)
WARNING: SEVERE DATA LOSS POSSIBLE.
Relocate
Block bitmap for group 4993 is not in group. (block 0)
Relocate
Inode bitmap for group 4993 is not in group. (block 0)
Relocate
Inode bitmap for group 21631 is not in group. (block 171349112)
Relocate
Inode table for group 21631 is not in group. (block 0)
WARNING: SEVERE DATA LOSS POSSIBLE.
Relocate
fsck.ext3: e2fsck_read_bitmaps: illegal bitmap block(s) for /dev/sdb
[root@localhost ~]# fsck.ext3 -b 163840 /dev/sdb
e2fsck 1.35 (28-Feb-2004)
Block bitmap for group 4992 is not in group. (block 809140608)
Relocate
Inode bitmap for group 4992 is not in group. (block 5385)
Relocate
Inode table for group 4992 is not in group. (block 1295485238)
WARNING: SEVERE DATA LOSS POSSIBLE.
Relocate
Inode bitmap for group 21631 is not in group. (block 171349112)
Relocate
Inode table for group 21631 is not in group. (block 0)
WARNING: SEVERE DATA LOSS POSSIBLE.
Relocate
fsck.ext3: e2fsck_read_bitmaps: illegal bitmap block(s) for /dev/sdb
6，直接fsck -y修复分区，也是报一样的错误：
[root@localhost ~]# fsck.ext3 -y /dev/sdb
e2fsck 1.35 (28-Feb-2004)
Group deｓｃｒｉｐｔors look bad… trying backup blocks…
Block bitmap for group 4992 is not in group. (block 809140608)
Relocate? yes
Inode bitmap for group 4992 is not in group. (block 5385)
Relocate? yes
Inode table for group 4992 is not in group. (block 1295485238)
WARNING: SEVERE DATA LOSS POSSIBLE.
Relocate? yes
Block bitmap for group 4993 is not in group. (block 0)
Relocate? yes
Inode bitmap for group 4993 is not in group. (block 0)
Relocate? yes
Inode table for group 4993 is not in group. (block 567580784)
WARNING: SEVERE DATA LOSS POSSIBLE.
Relocate? yes
Block bitmap for group 4994 is not in group. (block 0)
Relocate? yes
Block bitmap for group 21630 is not in group. (block 0)
Relocate? yes
Inode bitmap for group 21630 is not in group. (block 0)
Relocate? yes
Inode table for group 21630 is not in group. (block 0)
WARNING: SEVERE DATA LOSS POSSIBLE.
Relocate? yes
Block bitmap for group 21631 is not in group. (block 0)
Relocate? yes
Inode bitmap for group 21631 is not in group. (block 171349112)
Relocate? yes
Inode table for group 21631 is not in group. (block 0)
WARNING: SEVERE DATA LOSS POSSIBLE.
Relocate? yes
fsck.ext3: e2fsck_read_bitmaps: illegal bitmap block(s) for /dev/sdb
7，终极大法，用mke2fs -S重新生成超级块(注：此为实在没办法才执行的，不成功的话则全部数据会有丢失的可能)，修复成功了！！
[root@localhost ~]# mke2fs -S /dev/sdb
mke2fs 1.35 (28-Feb-2004)
/dev/sdb is entire device, not just one partition!
Proceed anyway? (y,n) y
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
365854720 inodes, 731688960 blocks
36584448 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
22330 block groups
32768 blocks per group, 32768 fragments per group
16384 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968,
102400000, 214990848, 512000000, 550731776, 644972544
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 39 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
8，终于可以将分区挂载上了：
[root@localhost ~]# mount /dev/sdb /test
9，用tune2fs -l查看/dev/sdb，发现状态为：not clean with errors，浏览文件发现其中还是有很多文件是损坏的：
[root@localhost ~]# tune2fs -l /dev/sdb
tune2fs 1.35 (28-Feb-2004)
Filesystem volume name:
Last mounted on:
Filesystem UUID: 2f3e8c46-64c0-4346-b7f6-edcfd457617a
Filesystem magic number: 0xEF53
Filesystem revision #: 1 (dynamic)
Filesystem features: resize_inode filetype sparse_super
Default mount options: (none)
Filesystem state: not clean with errors
Errors behavior: Continue
Filesystem OS type: Linux
Inode count: 365854720
Block count: 731688960
Reserved block count: 36584448
Free blocks: 720188790
Free inodes: 365854720
First block: 0
Block size: 4096
Fragment size: 4096
Reserved GDT blocks: 849
Blocks per group: 32768
Fragments per group: 32768
Inodes per group: 16384
Inode blocks per group: 512
Filesystem created: Fri Feb 18 14:37:14 2011
Last mount time: Fri Feb 18 14:37:33 2011
Last write time: Fri Feb 18 14:37:33 2011
Mount count: 1
Maximum mount count: 39
Last checked: Fri Feb 18 14:37:14 2011
Check interval: 15552000 (6 months)
Next check after: Wed Aug 17 14:37:14 2011
Reserved blocks uid: 0 (user root)
Reserved blocks gid: 0 (group root)
First inode: 11
Inode size: 128
Default directory hash: tea
Directory Hash Seed: 72bc7ce8-d9db-40c4-8ee8-85e169dd4bc5
10，只有再用fsck修复下/dev/sdb，分区2T多，修复了9个小时：
[root@localhost ~]# fsck.ext3 -y /dev/sdb
e2fsck 1.35 (28-Feb-2004)
/dev/sdb contains a file system with errors, check forced.
Pass 1: Checking inodes, blocks, and sizes
Journal inode is not in use, but contains data. Clear? yes
Inode 177963137 is in use, but has dtime set. Fix? yes
Inode 177963137 has imagic flag set. Clear? yes
Inode 177963147 is in use, but has dtime set. Fix? yes
Inode 177963147 has imagic flag set. Clear? yes
Inode 177963155 is in use, but has dtime set. Fix? yes
Inode 177963155 has imagic flag set. Clear? yes
Inode 177963156 is in use, but has dtime set. Fix? yes
Inode 177963156, i_blocks is 4294967295, should be 0. Fix? yes
Inode 177963155 has compression flag set on filesystem without compression support. Clear? yes
Inode 177963155 has INDEX_FL flag set but is not a directory.
11，修复完成后，/dev/sdb分区能够正常使用，此时发现文件系统变成ext2的了：
[root@localhost ~]# df -hT
Filesystem Type Size Used Avail Use% Mounted on
/dev/sda3 ext3 49G 36G 11G 78% /
/dev/sda6 ext3 812G 750G 22G 98% /bk
/dev/sda1 ext3 122M 13M 103M 12% /boot
none tmpfs 3.9G 0 3.9G 0% /dev/shm
/dev/sda2 ext3 49G 3.2G 43G 7% /opt
/dev/sdb ext2 2.7T 2.3T 349G 87% /test
12，用tune2fs -j把分区转成ext3：
[root@localhost ~]# tune2fs -j /dev/sdb
tune2fs 1.35 (28-Feb-2004)
Creating journal inode: done
This filesystem will be automatically checked every 39 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
13，成功了，分区状况也正常了，分区大部份数据还在，也能正常使用了，over：
[root@localhost ~]# tune2fs -l /dev/sdb
tune2fs 1.35 (28-Feb-2004)
Filesystem volume name:
Last mounted on:
Filesystem UUID: 2f3e8c46-64c0-4346-b7f6-edcfd457617a
Filesystem magic number: 0xEF53
Filesystem revision #: 1 (dynamic)
Filesystem features: has_journal resize_inode filetype sparse_super large_file
Default mount options: (none)
Filesystem state: clean
Errors behavior: Continue
Filesystem OS type: Linux
Inode count: 365854720
Block count: 731688960
Reserved block count: 36584448
Free blocks: 120881374
Free inodes: 360051869
First block: 0
Block size: 4096
Fragment size: 4096
Reserved GDT blocks: 849
Blocks per group: 32768
Fragments per group: 32768
Inodes per group: 16384
Inode blocks per group: 512
Filesystem created: Fri Feb 18 14:37:14 2011
Last mount time: Mon Mar 7 16:52:54 2011
Last write time: Tue Mar 15 11:45:42 2011
Mount count: 4
Maximum mount count: 39
Last checked: Fri Feb 18 22:44:35 2011
Check interval: 15552000 (6 months)
Next check after: Wed Aug 17 22:44:35 2011
Reserved blocks uid: 0 (user root)
Reserved blocks gid: 0 (group root)
First inode: 11
Inode size: 128
Journal inode: 8404993
Default directory hash: tea
Directory Hash Seed: 72bc7ce8-d9db-40c4-8ee8-85e169dd4bc5