Convert an ext3 file system into ext4

Ext4 file system provides better performance and faster file system check than the ext3 file system.
If you want to convert your existing file systems,the the first requirement is with the kernel.


Type
uname -a 


and make sure it is higher than 2.6.28.
To switch over to the Ext4drivers without changing any files,edit the fstab file located in /etc and replace every occurrence of ext3 to ext4.
Now issue:


sudo tune2fs -o extents,uninit_bg,dir_index <dev>


where dev stands for disk edited in the previous step.
As for example,if my disk was /dev/sda1, then I would do:


sudo tune2fs -o extents,uninit_bg,dir_index dev/sda1


Now restart your computer and do:


grub-install <dev> 


to install Grub to latest build.
Now, new files will be utilizing the features of new file system and old ones will be using ext3.