[LAU] USB, realtime, practical considerations

Hi Folks Whilst my 2.6.24.7-rt17 kernel and disabling all hardware and services unneeded for audio seems to have gotten rid of those nasty xruns, I live in fear that they will return. My main worry is how I organise my USB devices. My laptop (ThinkPad Z61m) has 3 USB ports. I have several devices that need to be connected to them, meaning that I need to use USB hubs. Here are some assumptions (or guesses) that I have made, on which I would appreciate comment: * It would be best to balance the devices across the 3 ports. * My soundcard is a Behringer UCA202, capable of sampling at a maximum of 48kHz @ 16bits x 2 channels. I'm guessing that this will have the greatest data rate of all attached devices. - Should it have its own port? - Can USB 2.0 take more than this (like another device?) - Anyone know how to set the sampling rate on this device through Linux? Just specify in Jack setup? * Now that I know that I can run USB to MIDI devices through a powered hub (thanks David), I was thinking of of hooking the following into a 7-port hub: - iPod cable (no iPod on the end, so no burden.) - cellphone cable (as per iPod cable.) - external USB QWERTY keyboard (don't have desk space for this when doing audio work, so hope it won't be transmitting any data.) - trackball (only transmitting when wiggled (I hope) - which should not occur when recording is going on.) - USB floppy drive (not in use when recording.) - USB to MIDI interface - Another USB to MIDI interface - is it too much to have 2 of these on the same hub? If not, would it take a third? Cheers M -- Matthew Smith Smiffytech - Technology Consulting & Web Application Development Business: http://www.smiffytech.com/ Personal: http://www.smiffysplace.com/ LinkedIn: http://www.linkedin.com/in/smiffy