CentOS 5: Converting Ext3 to Ext4

Ext4 (fourth extended file system) is the successor of current widely used Ext3 filesystem in Linux.

Since Ext4 filesystem already in the market, we can fully utilise this and improve IO (input/output) performance. Ext4 is well-known to be good in handling large storage, reduce up to 9 times of file system checking (fsck) time compare to Ext3 (refer to this) and also checksums in the journal.

Variables as follow:

OS: CentOS 5.6 64bit
Kernel version: 2.6.18-238.19.1.el5
Backup partition: /backup (mount from /dev/sdb)

1. First of all, its recommended to backup everything first. We will us ‘dd‘ command to backup the whole partition to another hard disk. That hard disk is attached via SATA cable. We will format the backup hard disk with ext3 filesystem and and mount as /backup partition:

$ fdisk /dev/sdb
Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
Partition number (1-4): 1
First cylinder (1-3916, default 1):
Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-3916, default 3916):
Using default value 3916
Command (m for help): w
The partition table has been altered!

The sequence I press in the keyboard is: n > p > 1 > enter > enter > w

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