I've seen a thread where it is stated that to ensure good performance (in terms of speed) the harddisk should be in DMA mode. i therefore ask 2 questions:

(1) how can i know whether my hd is operating in DMA or not (I'm using RH9)

(2) if it is not enabled, how can i do it, and does it involve risks?

THanks.

Do (shouldn't need to be root)

% hdparm /dev/hdc (or whatever your drive is)

and look for a line:

using_dma = 1 (on)

If it's off, log in as root and do 'hdparm -d1 /dev/hdc'. Then you should be OK. You can use 'hdparm -tT' to test performance. DMA makes a huge difference in disk performance.

Apparently DMA can cause problems and destroy data. I'm not sure how to check your hardware, other than by trying it out. I think it is mainly a problem with older systems. All hardware I've tried going back maybe 6-7 years gave no problems.

you should have to be root to issue the command hdparm, unless you have given a normal user privledges to issue this command.