modprobe ext4dev
tune2fs -E test_fs /dev/sdb1
mount /dev/sdb1 /mnt/sdb1

1. Create an ext2 filesystem
   • Create a regular file (filled with zeros) which will be the container for our file system.

[root@f11 ~]# dd if=/dev/zero of=fakedisk bs=1k count=10000

• Find the first unused loop device.

[root@f11 ~]# losetup –f
/dev/loop0

• Use the losetup command to associate file fakedisk with /dev/loop0.

[root@f11 ~]#  losetup /dev/loop0 fakedisk

• Create a ext2 file system in the container.

[root@f11 ~]#  mkfs -t ext2 /dev/loop0

1. Convert the ext2 filesystem to ext3
   • Convert ext2 filesystem to ext3.

[root@f11 ~]# tune2fs –j /dev/loop0
Tune2fs 1.41.4 (27-Jan-2009)
Creating journal inode: done
This filesystem will be automatically checked every 22 mounts or
180 days, whichever comes first. Use tune2fs –c or –i to override.

1. Convert the ext3 filesystem to ext4
   • Convert the ext3 filesystem to ext4, verify, and remove the loop device.

[root@f11 ~]# tune2fs –O dir_index,uninit_bg /dev/loop0
tune2fs 1.41.4 (27-Jan-2009)

• Please run e2fsck on the filesystem.

[root@f11 ~]# e2fsck –pf /dev/loop0
/dev/loop0: Group descriptor 0 checksum is invalid.  FIXED.

1. Convert the ext2 filesystem to ext4

[root@f11 ~]# tune2fs –O dir_index,uninit_bg,has_journal /dev/ram0
tune2fs 1.41.4 (27-Jan-2009)
Please run e2fsck on the filesystem.
Creating journal inode: done
This filesystem will be automatically checked every 39 mounts or
180 days, whichever comes first. Use tune2fs –c or –i to override.
[root@f11 ~]# e2fsck –pf /dev/ram0
/dev/ram0: Group descriptor 0 checksum is invalid.  FIXED.
/dev/ram0: 140/4096 files (0.7% non-contiguous), 3291/16384 blocks

• Converting EXT2 Filesystems to EXT3/EXT4
• ext2 -> ext3