Brad Campbell wrote:

Ok, so after a couple of reboots with max_sector set to 200 the problem 
re-occurs.

It must be something to do with programming the controller or timing or 
some other issue.

I have worked around it by putting my 2 raid-0 drives on my spare 
promise ports, and at UDMA100 with transfers of 2048 sectors they behave 
fine no matter what I throw at them.

Scratch that. After a couple of days if intensive testing/rebooting and abuse they play up on the
Promise controller in exactly the same failure mode. Just far harder to trigger.

I have removed these bridge board from my system now and thus the problem no longer exists. I'm a
little concerned that this might show itself for other people in the future but then I guess most
sane people buy SATA hard disks rather than re-use old ATA drives with bridge boards.
Cross that bridge if we come to it I guess.

Regards,
Brad (again and again and again)