This is one of those tips that are handy when you upgrade or have a partition already formatted and with data, and you realize that it is ext2!, there is no need to re-format it, or erase the data, just convert it !
When you see the partition type, 83 is used for a Linux partition, no matter if it is ext2 or ext3.
The Ext3 filesystem is an Ext2 filesystem with a journal file and some filesystem driver additions making the filesystem journalized.
Converting from Ext2 to Ext3
The conversion procedure is simple enough. Imagine /dev/sdb1 mounted as /data – the procedure would be as follows:
Log in as root
Make sure /etc/fstab has /dev/sdb1 mounted to /data as ext2, read write
If you can't unmount it, then remount it read only (mount -o remount,ro /dev/sdb1)
tune2fs -j /dev/sdb1
Edit /etc/fstab, and for /dev/sdb1, change ext2 to ext3
mount /dev/sdb1 /data, or mount -a
Check if the partition was correctly mounted:
mount | grep /dev/sdb1
If it's not shown as ext3, reboot (shutdown -r now)
if still not, troubleshoot ...
Otherwise, you're done.
A few explanations are in order.
The tune2fs command creates the journal file, which is kept in a special inode on the device (by default). You then must change the /etc/fstab entry to reflect it's a journalling filesystem, and then mount it.
You can check a full article describing other procedures in: