I see. I also noticed, that I can't switch on DMA transfer for neither hda nor hdc. without DMA disk access is really poor. It cannot be a big problem since it works with KNOPPIX 3.2 which also uses a 2.4.20 kernel. I guess the RedHat 2.4.20 kernel is missing the necessary DMA support. The question is, which kernel configuration parameter is the one?