Ext2到Ext3转换

在U盘上进行一次完整的文件系统创建转换，很多人应该没有用过mkfs.ext2（其实是mke2fs这个命令）这个命令来创建文件系统，大多数的时候都是在安装系统时已经完成了文件系统的创建，下面先看看如何使用mkfs.ext2来创建文件系统（这里需要root权限）：

[cocobear@cocobear minix]$ sudo mkfs.ext2 /dev/sdb 
mke2fs 1.40.4 (31-Dec-2007)
/dev/sdb is entire device, not just one partition!
Proceed anyway? (y,n) y
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
31360 inodes, 125440 blocks
6272 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=67371008
16 block groups
8192 blocks per group, 8192 fragments per group
1960 inodes per group
Superblock backups stored on blocks: 
        8193, 24577, 40961, 57345, 73729

Writing inode tables: done                            
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 24 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.

从Filesystem label= 开始解释，mkfs.ext2可以通过-L来指定文件系统的卷标，这里我们没有指定，因此为空；
OS type: Linux：mkfs.ext2在创建文件系统时检查操作系统的类型；
Block size=1024 (log=0)：ext2文件系统是由一个个的block组成，这里给出来新创建的block的大小，1024bytes，当然也可以使用-b选项手动指定block的大小，一般情况下block大小为1024bytes或4096bytes；
Fragment size=1024 (log=0)：fragment在这里是没有意义的，因为ext2文件系统不支持fragment，我们可以直接忽略。
31360 inodes, 125440 blocks：总共生成的inodes与blocks的数量，block数量我们可以通过U盘的大小来计算出来，首先使用fdisk来得到U盘的大小，该U盘的大小为：128450560 bytes，因为我们使用的block大小为1024 bytes，因此总block数为：128450560 bytes / 1024 =125400。

6272 blocks (5.00%) reserved for the super user：在ext2文件系统的创建时候默认会为root用户保留5%的空间，这个可以-m选项来指定。

First data block=1：表示数据从第一个block开始。

Maximum filesystem blocks=67371008：一个文件系统

16 block groups：一共有16个block分组；

8192 blocks per group, 8192 fragments per group：每个分组有8192个block；

1960 inodes per group：每个组有1960个inode；

Superblock backups stored on blocks:
8193, 24577, 40961, 57345, 73729
超级块在以前这几个block上进行了备份。

当然在文件系统创建好后也可以使用dumpe2fs或者tune2fs来获得上面的信息，tune2fs正是我们下面需要使用的转换工具。

[cocobear@cocobear ~]$ sudo dumpe2fs /dev/sdb 
dumpe2fs 1.40.4 (31-Dec-2007)
Filesystem volume name:   <none>
Last mounted on:          <not available>
Filesystem UUID:          d8d7cb8e-4cc0-4d91-b7e3-dcbc3f403345
Filesystem magic number:  0xEF53
Filesystem revision #:    1 (dynamic)
Filesystem features:      resize_inode dir_index filetype sparse_super
Filesystem flags:         signed directory hash 
Default mount options:    (none)
Filesystem state:         not clean
Errors behavior:          Continue
Filesystem OS type:       Linux
Inode count:              31360
Block count:              125440
Reserved block count:     6272
Free blocks:              119925
Free inodes:              31349
First block:              1
Block size:               1024
Fragment size:            1024
Reserved GDT blocks:      256
Blocks per group:         8192
Fragments per group:      8192
Inodes per group:         1960
Inode blocks per group:   245
Filesystem created:       Sat Apr 26 08:13:03 2008
Last mount time:          Sat Apr 26 17:13:06 2008
Last write time:          Sat Apr 26 17:13:06 2008
Mount count:              1
Maximum mount count:      31
Last checked:             Sat Apr 26 08:13:03 2008
Check interval:           15552000 (6 months)
Next check after:         Thu Oct 23 08:13:03 2008
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:      f8b3e365-54e7-43b1-ad25-b3270db87684

Group 0: (Blocks 1-8192)
  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 261-505 (+260)
  7673 free blocks, 1949 free inodes, 2 directories
  Free blocks: 520-8192
  Free inodes: 12-1960
………………

首先卸载掉U盘，然后使用下面的命令：

[cocobear@cocobear ~]$ sudo tune2fs -j /dev/sdb
tune2fs 1.40.4 (31-Dec-2007)
Creating journal inode: done
This filesystem will be automatically checked every 31 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.

然后我们再来看一下文件系统信息：

[cocobear@cocobear ~]$ sudo dumpe2fs  /dev/sdb
dumpe2fs 1.40.4 (31-Dec-2007)
Filesystem volume name:   <none>
Last mounted on:          <not available>
Filesystem UUID:          d8d7cb8e-4cc0-4d91-b7e3-dcbc3f403345
Filesystem magic number:  0xEF53
Filesystem revision #:    1 (dynamic)
Filesystem features:      has_journal resize_inode dir_index filetype sparse_super
Filesystem flags:         signed directory hash 
Default mount options:    (none)
Filesystem state:         not clean
Errors behavior:          Continue
Filesystem OS type:       Linux
Inode count:              31360
Block count:              125440
Reserved block count:     6272
Free blocks:              115812
Free inodes:              31348
First block:              1
Block size:               1024
Fragment size:            1024
Reserved GDT blocks:      256
Blocks per group:         8192
Fragments per group:      8192
Inodes per group:         1960
Inode blocks per group:   245
Filesystem created:       Sat Apr 26 08:13:03 2008
Last mount time:          Sat Apr 26 17:13:06 2008
Last write time:          Sat Apr 26 17:55:15 2008
Mount count:              1
Maximum mount count:      31
Last checked:             Sat Apr 26 08:13:03 2008
Check interval:           15552000 (6 months)
Next check after:         Thu Oct 23 08:13:03 2008
Reserved blocks uid:      0 (user root)
Reserved blocks gid:      0 (group root)
First inode:              11
Inode size:               128
Journal inode:            12
Default directory hash:   tea
Directory Hash Seed:      f8b3e365-54e7-43b1-ad25-b3270db87684
Journal size:             4113k

Group 0: (Blocks 1-8192)
  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 261-505 (+260)
  5113 free blocks, 1948 free inodes, 2 directories
  Free blocks: 520-5632
  Free inodes: 13-1960

从这里“Filesystem features: has_journal resize_inode dir_index filetype sparse_super”我们可以看到已经加入了ext3的日志功能。

Comments

luguo: tune2fs很强大嘛～～没用过的说～！