On 08/12/2009 01:34 AM, Ian Murray wrote: ...
Under Ubuntu (NB the drive was under /dev/sdb under Ubuntu - is this a clue?!?):-
Some HP machines have the same symptoms you describe:
Slow disk IO with CentOS, fast with Fedora.
The cure is to append
hda=noprobe hdc=noprobe
to the startup parameters in /boot/grub/grub.conf.
Mogens