19.6 Creating a File System on a File

The software described in this documentation is either in Extended Support or Sustaining Support. See https://www.oracle.com/us/support/library/enterprise-linux-support-policies-069172.pdf for more information.
Oracle recommends that you upgrade the software described by this documentation as soon as possible.

19.6 Creating a File System on a File

To create a file system on a file within another file system:

Create an empty file of the required size, for example:

# dd if=/dev/zero of=/fsfile bs=1024 count=1000000
1000000+0 records in
1000000+0 records out
1024000000 bytes (1.0 GB) copied, 8.44173 s, 121 MB/s

Create a file system on the file:

# mkfs.ext4 -F /fsfile
mke2fs 1.41.12 (17-May-2010)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
62592 inodes, 250000 blocks
12500 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=260046848
8 block groups
32768 blocks per group, 32768 fragments per group
7824 inodes per group
Superblock backups stored on blocks: 
	32768, 98304, 163840, 229376

Writing inode tables: done                            
Creating journal (4096 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 33 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.

Mount the file as a file system by using a loop device:

# mount -o loop /fsfile /mnt

The file appears as a normal file system:

# mount
...
/fsfile on /mnt type ext4 (rw,loop=/dev/loop0)
# df -h
Filesystem            Size  Used Avail Use% Mounted on
...
/fsfile               962M   18M  896M   2% /mnt

If required, create a permanent entry for the file system in /etc/fstab:

/fsfile          /mnt      ext4    rw,loop     0 0