Testing disk I/O?

[Tom Horsley]

I know about the smart tools, but they run disk tests
pretty much entirely within the disk drive (I think?).

Is there a good tool for testing the whole disk I/O
system that will wind up exercising the disk, the
controller/chipset, etc? (Hopefully available in the
fedora repos).

I have a feeling something is going funny in the head
on my system and the smart disk tests report all OK
(as does a few passes of memtest86+). I want to get
the motherboard into the mix now.