The filesystem used in the vast majority of Linux (and to a lesser extent on other Unix) distributions is the ext3 filesystem, which stands for extended filesystem. Slashdot recently pointed to an article on IBM DeveloperWorks discussing the new ext4 filesystem currently in development, and some of its new features. So what is a filesystem really?

The ext4 filesystem has been around for a while as experimental code in GNU/Linux distributions. Recently one distribution decided to make it the default for an install.

Over the weekend, I converted my laptop to use the ext4 filesystem. So far so good! So far I’ve found one bug as a result of my using ext4 in production (if delayed allocation is enabled, i_blocks doesn’t get updated until the block allocation takes place, so files can appear to have 0k blocksize right after they are created, which is confusing/unfortunate), but nothing super serious yet.

With the EXT4 file-system having been stabilized with the Linux 2.6.28 kernel, the Ubuntu developers are preparing to adopt this evolutionary Linux file-system update. EXT4 will not replace EXT3 as the default file-system until at least Ubuntu 9.10, but as of yesterday, Ubuntu 9.04 now has install-time support for EXT4.

Mason said he would like to see Btrfs ultimately replacing existing Linux filesystems like the popular Ext3 and Ext4 systems that are often the default on enterprise Linux distributions.

I did mention that the new filesystem - ext4 is stable, fast and backward compatible with ext2 and ext3. Today, we will look at how you can upgrade your existing ext3 filesystem to ext4 without reformating your hard disk.

Ext4 is the latest in a long line of Linux® file systems, and it's likely to be as important and popular as its predecessors. As a Linux system administrator, you should be aware of the advantages, disadvantages, and basic steps for migrating to ext4.

This article is meant to serve as a guide for migrating a live system from ext3 to an ext4 filesystem, including migration of files to use extents, a major feature in ext4.

You can convert your existing Ext3 filesystem to Ext4 with an easy procedure.Things to remember
* Unmount the filesystem before convert
* Filesystem must be non-root
This way you can improve the performance, storage limits and features of your existing filesystem without reformatting and/or reinstalling your OS and softwares.