System unresponsitive when copying HD/HD

[Delta <birtl00@dmi.usherb.ca>]

Hi,

I backup my linux partition once a month from my second IDE drive to an
empty partition
on the first IDE disk. I have about 2.8 Gig to copy, and I use <cp -ax /
/mnt/hd> to do the copy.

While cp is copying from the second hard disk to the first hard disk,
I find my system performance
drop VERY sharply.  X is sloppy, even bash takes many seconds to
respond.  I using two
recent IDE disk (Fudjisu 13 gig, Maxtor 20 Gig), so I'm wondering why
the system is so slow?  My mobo is a FIC SD11 and I have an athlon
550 Mhz.

I tried renicing the process priority to 20, but I don't see any
improvement on system usability.
Hard disk activity is still frenzy, even if there are other task
runnable (X, g++ jobs).
Note that I'm running as root when I'm doing the copy.

So I'd like to know why the linux kernel can't schedule the task less
often?
I guess that copying file doesn't eat too many CPU cycles, but is
running almost all the time
in kernel mode doing I/O... Is there a way to prevent a process from
"hogging" the hard disk like that?
It's pretty annoying when the system is sluggish like that.

Thanks a lot,
Laurent Birtz <birtl00@dmi.usherb.ca>

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