ext4文件系统分配空间 格式化

tarena@ubuntu:~/porting/busybox-1.21.1$ dd if=/dev/zero of=rootfs.ext4 bs=1k count=8192
记录了8192+0 的读入
记录了8192+0 的写出
8388608字节(8.4 MB)已复制，0.0348157 秒，241 MB/秒
tarena@ubuntu:~/porting/busybox-1.21.1$ sudo mkfs
[sudo] password for tarena:
Usage: mkfs [options] [-t type fs-options] device [size]

Options:
 -t, --type=TYPE  file system type, when undefined ext2 is used
     fs-options   parameters to real file system builder
     device       path to a device
     size         number of blocks on the device
 -V, --verbose    explain what is done
                  defining -V more than once will cause a dry-run
 -V, --version    output version information and exit
                  -V as version must be only option
 -h, --help       display this help and exit

For more information see mkfs(8).
tarena@ubuntu:~/porting/busybox-1.21.1$ hexdump -C rootfs.ext4
00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00800000
tarena@ubuntu:~/porting/busybox-1.21.1$ sudo  mkfs.ext4 rootfs.ext4  //格式化
mke2fs 1.42 (29-Nov-2011)
rootfs.ext4 is not a block special device.
无论如何也要继续? (y,n) y
Discarding device blocks: 完成                           
文件系统标签=
OS type: Linux
块大小=1024 (log=0)
分块大小=1024 (log=0)
Stride=0 blocks, Stripe width=0 blocks
2048 inodes, 8192 blocks
409 blocks (4.99%) reserved for the super user
第一个数据块=1
Maximum filesystem blocks=8388608
1 block group
8192 blocks per group, 8192 fragments per group
2048 inodes per group

Allocating group tables: 完成                           
正在写入inode表: 完成                           
Creating journal (1024 blocks): 完成
Writing superblocks and filesystem accounting information: 完成