I don't know any deep details about USB, except that I _know_ that it is a serial bus, but considering following:
1) I can read/write 45 MByte/s from harddrive to harddrive on the E-IDE bus (theoretically 100 MByte/s), so the speed of the harddrive I read/write from/to is probably the bottleneck. 2) if I understand it right, an USB controller is connected to to the PCI bus and there can be many separate USB controller on one PC 3) the theoreticall speed of USB (430 MByte/s?) is much higher as the experienced 15 MByte/s, probably due to slow controller on the side of the external storage media, so maybe even on one USB line I will have the chance to use it full capacity connecting many slow devices (I can't imagine, that USB goes down with the speed to the speed of the slowest component connected, does it?) 4) with 45 MByte/s I could theoretically simultaneously supply three separate data streams to three USB controller writing with 15 MByte/s each out to the external storage media. 5) watching the low CPU usage while writing to USB shows me, that CPU-time is not a problem. I still see a chance of writing truly simultaneously to several devices connected via USB. Please let me know if I am wrong in any of the points (1-5) or if my conclusion is based on wrong assumptions or if I use a wrong way of infering. By the way: I was not thought about bus design at university, so what I know about it is comes from self-study :-). Claudio P.S. Your message appears in my Outlook Express as one having no content, but an attachment, so I can't read it directly. > Is there maybe a way to use a direct DMA > transfer to multiple target destinations > (I copy to drives connected via USB ports) ? Think about what USB stands for. Then reconsider whether you'll ever have the chance of writing truly simultaneously to several devices connected via USB... And then, as an extra exercise, think about why it takes so long when several different jobs are done in parallel, writing to devices connected via USB. Bus design... Don't they teach anything at uni these days? ;) -- --- Heiko. -- http://mail.python.org/mailman/listinfo/python-list
