[CentOS] Question on server speed

Tue Aug 6 13:22:17 UTC 2019
Chris Adams <linux at cmadams.net>

Once upon a time, Warren Young <warren at etr-usa.com> said:
> 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.

Yes, you have described USB.

The newer storage-specific transfer modes for USB3 try to do better, but
it's still a shared bus and requires lots of CPU "assistance" to do just
about anything.  And there are lots of systems that have some USB3 and
some USB2 ports - accidentally plug your external SSD into a USB2 port
and start copying lots of data, and the system can just about appear to
be hung.  Welcome to USB!

Chris Adams <linux at cmadams.net>