ext3 vs ext4

Install any latest version of the kernel so that the ext4 patch can be applied to it.

yum -y install e4fsprogs

Then convert "/dev/sdb1" to EXT4 and run the following commands:

#cd /; umount /dev/sdb1
#tune2fs -O extents,uninit_bg,dir_index /dev/sdb1
Next run fsck

#fsck -pf /dev/sdb1
Now, simply mount the partition that you have converted.

#mount -t ext4 /dec/sdb1 /
The following steps are for converting "/boot" to "ext4" :

1. First convert the "/boot" file system as the ext4 file system using the commands above and then open the Grub file and add "rootfstype=ext4" as the kernel parameter.

#mkinitrd --with=ext4 --with=ext3 -f /boot/initrd-2.6.18-194.3.1.el5.img 2.6.18-194.3.1

#tune4fs -O extents,uninit_bg,dir_index /dev/mapper/VolGroup00-LogVolRoot
* Need to use tune4fs on ext4 filesystems instead of tune2fs. This is
only needed for RHEL5.

2. Now, run the command to update Grub:

# update-grub

3. Next, update your "/etc/fstabe" file so that it can be mounted as an ext4 file system.vi /etc/fstab
(change ext3 to ext4 for my / partition)

4. Than reboot the system.