Testing filesystems

I know - never touch a running system… but it’s fun still doin it. This time I am at testing filesystems for my system. But how should I do it?

On my gentoo notebook, the portage is located on its own partition - not only due to fragmentation reasons. This partition does not contain files worth a backup.

Ext4 is new in the kernel - This time I decided to give it a try as reiser 3.6 got pretty slow with that many and always changing files.