Upgrading the root file system on a Linode to ext4

The ext4 file system has been around for a while now, so I figured I'd migrate my Linode's ext3 partition to it for some of the reasons listed here.

The major downsides would be that I wouldn't be able to use some nice tools that Linode provide, such as their automatic partition resizing and automatic backup solution, and their rescue distribution, Finnix, doesn't support it.

Obviously you'd want to make sure you have a full backup before proceeding with this. I didn't, but I'm an idiot.

First you need to make sure you're using a recent kernel — probably 2.6.30 or higher. This is because some applications had made bad assumptions. I'm using the latest 2.6 Paravirt that Linode provides, which is 2.6.35.4-x86-_64-linode16. My system is Ubuntu 10.10 64-bit.

1. From the Linode Platform Manager, restart in rescue mode.
2. Run the following commands to update Finnix with a recent e2fsprogs that supports ext4:
   1. apt-get update
   2. apt-get install debian-archive-keyring e2fsprogs
3. Perform the actual ext4 conversion:
   1. tune2fs -O extents,uninit_bg,dir_index /dev/xvda (It will no longer be ext3 compatible after running this.)
   2. e2fsck -fDC0 /dev/xvda
4. Shutdown and boot up through the Linode Platform Manager
5. The system should automatically mount the partition as ext4.

Even though the system mounted the partition successfully I figured I'd change the /etc/fstab to reflect the new file system.

Links

• Upgrading fsck in Finnix on the fly
• Converting an ext3 file system to ext4