I am still unable to understand the difference between Ext2 and Ext3 file system.

I fully agree with MR Mosleh Saeidi  

ext2 :

– Introduced with kernel1.0 in1993

– Flexible can handle upto4TB

– super block feature increase file system performance

– ext2 reserve5% of disk space for root

– ext2 is popular on USB and other solid-state devices.

This is because it does not have a journaling function.

so it generally makes fewer reads and writes to the drive,

effectively extending the life of the device .

– NO journalalizm

ext3 :

– Provide all the feature of ext2 + journaling and backward compatibility .

– can upgrade ext2 to ext3 without loss of data.

– journaling feature speed up the system to recover the state after power-failure

or improper mount unmount etc.

– Example: In ext2 in an improper unmount or in-between power-off etc.. so in time

of receiver it checks whole file system .

But in ext3 it keeps record of uncommitted file transactions and checks applied

on on them so system will come back up in faster and quicker .

ext4:

– Introduced with kernel2.6.28

– Ext4 is a deeper improvement over Ext3

– support larger filesystem, faster checking, nanosecond timestamps,

and verification of the journal through checksums.

– It is backward and forward compatible with versions2 and3, so we can

mount a ext2 or ext3 filesystem as ext4 .

– The main benefits that ext4 has over ext3 are:

– faster time-stamping

– faster file system checking

– journaling check-sums

– extents (basically automatic space allocation to avoid fragmentation)

This is a really strange thing to ask "Please no copy-paste from net."

I will not copy it for the internet but will tell you to read it from Wikipedia because you said "I am still unable to understand the difference between Ext2 and Ext3 file system." The best way to memorize something is to work to get it and read it.

Ext2 has no journaling feature

Ext3 Journaling feature added

Very simple - Have you seen scan disk at Windows98/ME machines. When system went down without proper issue, hard disk will scan the file information on secotors and will fix the issue.

File information nodes is called as inode. In ext3, it will do the scanning at booting time automatically and clean the issues but ext2 doesnt have that feature. This is one of the advantage comparing to Ext2/Ext3 system. Same way, supporting size for a partition have difference in ext2/ext3. Ext3 journling system optimized file system.