IO Bus as the database limiting factor?

Hi, We've been looking at buying some new disks for our HP 9000 K410 Unix server. The server is basically used for a data warehouse on IDS (7.23, soon to be 7.30). As we need to buy a new IO bus to fit the disks (via fast/wide scsi's) we've been testing out the current system. By: 1. Creating multiple copies of a 50 Mbyte table on various disks on our current EMC raid box, 2. Running the same, simple, but long running query on these tables we believe we can see that a HP-PB (HP Precision Bus - maximum throughput 32 Mbits /s) becomes the limiting factor on I/O throughput. Two questions. Firstly does anyone know what is the throughput on an HP-HSC IO Bus? Secondly, does anyone have any experience of handling the situation where your disk arrays can provide data faster than the IO bus can handle? As we use parallelism as much as we can, we seem to be getting to the stage where database tuning is going to be pointless as the IO subsystem is rapidly flooded by almost any large query. Thanks for any comments Martyn Hodgson martyn.hodgson@eaglestar.co.uk