Ok, so somewhere I though that the 2.4 kernel might be kind enough to use reasonable settings for disk performance. NnnNOOOOO! Of course not.

Controller perf shows 50-55MB/sec which is good for this box (I think it’s UDMA/33).
My disk performances were roughly 3 and 5 MB/sec. DMA was off. Using my happy script below gained me a fill 3x performance for both disks.

my little script