Out of bounce buffers

Hi 

I have had a weird issue since the change in April where the SATA Port
multipliers was introduced. The system started issuing "DATA load FAILURE"
in the ata-dmaload every time that disk subsystem got loaded. Because the
code prior from 10/04-2008 worked fine and Ignored the problem and simply
used the code prior to the SATA
Port multiplier was introduced. The reason was twofold - One I did not time
to investigate and two I suspected it could be a hw error - using cheap SATA
disks.

Well finally I have had time to investigate and the problem occurs because
the system "runs out of bounce buffers" 

I have tested the entire disk for errors using a Hitachi tools and there
seems to no problems - down to the degree that I can get the system to work
with the current ATA subsystem as long as I only use one disk ;-)
Regardless of which of the 4 disks - 

however if I add a second disk to the subsystem it will eventually (after
17-40GB of restores) give me a "DATA load failures" - Naturally I suspected
the disk drives - however as I said - I can fully restore without the error
occurring as long as I only use one disk

Puzzled by this I started plastering the code with printf's to see what
happened - patch included just FYI - 
It turns out that the kernel runs out of bounce buffers - which is very
surprising - Can anybody give any advice on this?