Virtual file system in Linux

如果你想要在Linux系統中從一個既有的partition去虛擬另一個partition的話，Virtual file system是一個蠻不錯的小技巧。

Step1. 建立一個空檔:

[root@localhost ruckus]# cd /tmp/

[root@localhost tmp]# dd if=/dev/zero of=vs_file bs=1M count=512

512+0 records in

512+0 records out

536870912 bytes (537 MB) copied，0.767225 秒，700 MB/s

Step2. 將空檔格式化成虛擬的檔案系統:

[root@localhost tmp]# mke2fs -j vs_file

mke2fs 1.39 (29-May-2006)

vs_file is not a block special device.

Proceed anyway? (y,n) y

Filesystem label=

OS type: Linux

Block size=1024 (log=0)

Fragment size=1024 (log=0)

131072 inodes, 524288 blocks

26214 blocks (5.00%) reserved for the super user

First data block=1

Maximum filesystem blocks=67633152

64 block groups

8192 blocks per group, 8192 fragments per group

2048 inodes per group

Superblock backups stored on blocks:

8193, 24577, 40961, 57345, 73729, 204801, 221185, 401409

Writing inode tables: done

Creating journal (16384 blocks): done

Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 21 mounts or

180 days, whichever comes first. Use tune2fs -c or -i to override.

Step3. 以一般掛載partition的方法掛載虛擬檔案系統:

[root@localhost tmp]# mount -o loop /tmp/vs_file /mnt/vf/

Step4. 驗證一下:

[root@localhost tmp]# mount | grep vs_file

/tmp/vs_file on /mnt/vf type ext3 (rw,loop=/dev/loop0)

[root@localhost tmp]# cd /mnt/vf/

[root@localhost vf]# ls

lost+found

[root@localhost vf]# touch test

[root@localhost vf]# ls

lost+found test