使用dumpe2fs 查看superblock的信息：

[root@localhost ~]# dumpe2fs /dev/sda1 

dumpe2fs 1.39 (29-May-2006)

Filesystem volume name:   /boot 文件系统名

Last mounted on:          <not available>

Filesystem UUID:          b20ffbe6-f56d-4eee-a3a2-22145aa88e36

Filesystem magic number:  0xEF53

Filesystem revision #:    1 (dynamic)

Filesystem features:      has_journal ext_attr resize_inode dir_index filetype needs_recovery sparse_super

Default mount options:    user_xattr acl 预设挂载的参数

Filesystem state:         clean  文件系统没问题

Errors behavior:          Continue

Filesystem OS type:       Linux

Inode count:              26104  inode总数

Block count:              104388 block总数

Reserved block count:     5219

Free blocks:              89087  剩余block

Free inodes:              26070  剩余inode

First block:              1

Block size:               1024   每个block大小

Fragment size:            1024

Reserved GDT blocks:      256

Blocks per group:         8192

Fragments per group:      8192

Inodes per group:         2008

Inode blocks per group:   251

Filesystem created:       Tue Oct 21 15:21:01 2014

Last mount time:          Wed Nov  5 09:55:55 2014

Last write time:          Wed Nov  5 09:55:55 2014

Mount count:              19

Maximum mount count:      -1

Last checked:             Tue Oct 21 15:21:01 2014

Check interval:           0 (<none>)

Reserved blocks uid:      0 (user root)

Reserved blocks gid:      0 (group root)

First inode:              11

Inode size:  128 每个inode大小

Journal inode:            8

Default directory hash:   tea

Directory Hash Seed:      61428c96-2452-4c54-b4e4-21fe31cceb6b

Journal backup:           inode blocks

Journal size:             4114k

Group 0: (Blocks 1-8192) 第一个data group 内容，包含block开始和结束号码

  Primary superblock at 1, Group descriptors at 2-2

  Reserved GDT blocks at 3-258

  Block bitmap at 259 (+258), Inode bitmap at 260 (+259)

  Inode table at 261-511 (+260)

  479 free blocks, 1991 free inodes, 2 directories

  Free blocks: 4642-5120

  Free inodes: 18-2008

Group 1: (Blocks 8193-16384)

  Backup superblock at 8193, Group descriptors at 8194-8194

  Reserved GDT blocks at 8195-8450

  Block bitmap at 8451 (+258), Inode bitmap at 8452 (+259)

  Inode table at 8453-8703 (+260)

  4420 free blocks, 1991 free inodes, 1 directories

  Free blocks: 11808-12288, 12296-12800, 12810-13312, 13349-15360, 15362-15872, 15977-16384

  Free inodes: 2026-4016

Group 2: (Blocks 16385-24576)

  Block bitmap at 16385 (+0), Inode bitmap at 16386 (+1)

  Inode table at 16387-16637 (+2)

  7939 free blocks, 2008 free inodes, 0 directories

  Free blocks: 16638-24576

  Free inodes: 4017-6024

Group 3: (Blocks 24577-32768)

  Backup superblock at 24577, Group descriptors at 24578-24578

  Reserved GDT blocks at 24579-24834

  Block bitmap at 24835 (+258), Inode bitmap at 24836 (+259)

  Inode table at 24837-25087 (+260)

  7681 free blocks, 2008 free inodes, 0 directories

  Free blocks: 25088-32768

  Free inodes: 6025-8032

Group 4: (Blocks 32769-40960)

  Block bitmap at 32769 (+0), Inode bitmap at 32770 (+1)

  Inode table at 32771-33021 (+2)

  7939 free blocks, 2008 free inodes, 0 directories

  Free blocks: 33022-40960

  Free inodes: 8033-10040

Group 5: (Blocks 40961-49152)

  Backup superblock at 40961, Group descriptors at 40962-40962

  Reserved GDT blocks at 40963-41218

  Block bitmap at 41219 (+258), Inode bitmap at 41220 (+259)

  Inode table at 41221-41471 (+260)

  7681 free blocks, 2008 free inodes, 0 directories

  Free blocks: 41472-49152

  Free inodes: 10041-12048

Group 6: (Blocks 49153-57344)

  Block bitmap at 49153 (+0), Inode bitmap at 49154 (+1)

  Inode table at 49155-49405 (+2)

  7939 free blocks, 2008 free inodes, 0 directories

  Free blocks: 49406-57344

  Free inodes: 12049-14056

Group 7: (Blocks 57345-65536)

  Backup superblock at 57345, Group descriptors at 57346-57346

  Reserved GDT blocks at 57347-57602

  Block bitmap at 57603 (+258), Inode bitmap at 57604 (+259)

  Inode table at 57605-57855 (+260)

  7681 free blocks, 2008 free inodes, 0 directories

  Free blocks: 57856-65536

  Free inodes: 14057-16064

Group 8: (Blocks 65537-73728)

  Block bitmap at 65537 (+0), Inode bitmap at 65538 (+1)

  Inode table at 65539-65789 (+2)

  7939 free blocks, 2008 free inodes, 0 directories

  Free blocks: 65790-73728

  Free inodes: 16065-18072

Group 9: (Blocks 73729-81920)

  Backup superblock at 73729, Group descriptors at 73730-73730

  Reserved GDT blocks at 73731-73986

  Block bitmap at 73987 (+258), Inode bitmap at 73988 (+259)

  Inode table at 73989-74239 (+260)

  7681 free blocks, 2008 free inodes, 0 directories

  Free blocks: 74240-81920

  Free inodes: 18073-20080

Group 10: (Blocks 81921-90112)

  Block bitmap at 81921 (+0), Inode bitmap at 81922 (+1)

  Inode table at 81923-82173 (+2)

  7939 free blocks, 2008 free inodes, 0 directories

  Free blocks: 82174-90112

  Free inodes: 20081-22088

Group 11: (Blocks 90113-98304)

  Block bitmap at 90113 (+0), Inode bitmap at 90114 (+1)

  Inode table at 90115-90365 (+2)

  7939 free blocks, 2008 free inodes, 0 directories

  Free blocks: 90366-98304

  Free inodes: 22089-24096

Group 12: (Blocks 98305-104387)

  Block bitmap at 98305 (+0), Inode bitmap at 98306 (+1)

  Inode table at 98307-98557 (+2)

  5830 free blocks, 2008 free inodes, 0 directories

  Free blocks: 98558-104387

  Free inodes: 24097-26104

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dumpe2fs查看superblock