Generally you need to be root to use hdparm.
I am root! I wouldn't imagine it working it with a non-priveleged user.There seems to be a gerneral problem with hdparm not being happy under the 2.4 kernel -- if I boot 2.2.18 again it works fine.
Even more generally you shouldn't need to use hdparm with 2.4.x kernels. 2.4.x has much better IDE support.
I get much better benchmark results with DMA set on. -- Chris Howells E-Mail: chrish@gmx.co.uk ICQ: 93699029 Web: http://www.chowells.uklinux.net