Convert ext3 to ext4
From Birnam Designs Wiki
Perform a system update to make sure you have the latest kernel and grub boot loader.
$ sudo apt-get update $ sudo apt-get upgrade
Enable the Ext4 features (Once you run this command you will no longer be able to mount this partition using the Ext3 file system!)
$ sudo tune2fs -O extents,uninit_bg,dir_index /dev/sdb1
Run fsck to fix the disk structure we modified in the previous step with tune2fs
$ sudo e2fsck -fpDC0 /dev/sdb1
Update your fstab file to reflect our changes
/dev/sdb1 /media/sdb1 ext4 relatime,errors=remount-ro 0 1
When converting a drive with extents enabled, only new files will be created in the extents format. It will not convert existing files to use extents. However Ext4 can read both of them transparently.
