You could "nice" it. "man nice". Since there is likely to be a lot of I/O happening, it may not help much.
Ok, here's a noob question :) - What process would I nice?
If the drives are on the same channel, or other devices on the channel are also flooding the channel, that would be expected. Does "swapon -s" show a lot of swap being used? Does top give a clue? I suspect a lot of CPU may also be involved.
Swapon -s shows 0 being used, top shows cpu's next under 1%.
Thanks! jlc