I am newbie in redhat enterprise linux ES 3.0. May I know how do I configure its filesystem as reiserfs instead of ext3? If I am using ext3 then can I change it to reiserfs without erase my existing data? If Yes, How do I do?

Your helping is appreciated and thanks you!

I don't know of any tool that will convert an ext2/3 filesystem to reiserfs; they are fundamentally different filesystems.

In any case, you would be very well advised to take a backup of the complete filesystem image prior to changing anything as low-level as the filesystem type. And with a backup, you can just delete the partition, make a new one, then copy the files back across.

Also, please note that you are not necessarily going to gain very much by changing the filesystem; reiser tends to be slightly faster for some things but slightly slower for some others, and it's not any more reliable; if you really want a performance or reliability increase then I would look at getting a second hard-disk and setting up a software RAID (and putting your Reiser filesystem on that). http://www.tldp.org/HOWTO/Software-RAID-HOWTO.html

Also note that Reiserfs is NOT supported by Red Hat! If you call them with a problem regarding an issue with your filesystem on your ES 3.0 server and they discover you are running Reiserfs, they will not be able to support you.