On Aug 6, 2019, at 7:04 AM, Stephen John Smoogen <smooge at gmail.com> wrote: > > On Mon, 5 Aug 2019 at 19:49, Warren Young <warren at etr-usa.com> wrote: > >> On Aug 5, 2019, at 11:25 AM, Stephen John Smoogen <smooge at gmail.com> >> wrote: >>> >>> On Mon, 5 Aug 2019 at 13:17, Jerry Geis <jerry.geis at gmail.com> wrote: >>> >>>> an external SSD disk USB3 connected and the machine "freezes"... Why is >>>> that? >>>> >>> You may have a motherboard which is routing a lot through a single USB >>> controller. >> >> Ridiculous if true. Modern OSes solved the blocking I/O problem decades >> ago. >> > The OS can only do as much as the hardware allows. Back when we had serial mice, the most common data rate was 1200 bps. That’s 0.0012 Mbit/sec. If your 480 Mbit/sec USB-2 or 5/10/20 Mbit/sec USB-3 bus is so jammed up that it can’t trickle through that much data per second from the mouse while an SSD on the same bus is blocked on I/O, it’s dreck hardware.