Ubuntu 9.04 Supports Ext4
Since its addition to Kernel 2.6.28, the ext4 filesystem can be manually installed in the upcoming Ubuntu release.
Ubuntu 9.04 (Jaunty Jackalope), which has its official release in April 2009, will support the ext4 filesystem that is the successor to ext3. According to Ubuntu's Colin Watson, support for the ext4 partition is already in the installer as an option. Previously it was only possible by formatting an existing non-boot partition via mkfs.ext4 on the command line.
It was not so long ago that Ted Ts'o successfully installed ext4 on his own system and kernel developers merged it into the 2.6.28 mainline code. For a while there was a hitch in adopting ext4 because of an issue with initramfs, but work to get the filesystem into a production environment is well in gear.
The filesystem offers some advantages over its ext3 predecessor. It can handle data up to 16 Terabytes and filesystems up to an Exabyte (about a million Terabytes). It also allows for an unlimited number of subdirectories and manages data types better. Regular users will also benefit from ext4 in that regular consistency tests via fsck have proved it to be markedly faster, according to Ted Ts'o.
Ubuntu kernel team member Tim Gardner reported being "really impressed" with ext4 in that file deletion proved about 20 times faster than with ext3, and kernel build times were cut in half. He also included a few links to suggestions how to migrate ext3 to the new ext4.