Subject: Re: [OT] usb hubs
From: Peter M. Bagnall (pete@surfaceeffect.com)
Date: Sat Aug 19 2000 - 12:04:31 MDT
>Does anyone have a recommondation for a really high quality USB hub I
>could get that would be more likely to just plain work than the el
>cheapo hub she currently has? I want mom to have the best, and I want
>her system to work smoothly the way its suppose to.
I've found some strange effects with hubs. First question, is your hub
powered? If not that could be the problem. I have a Belkin ExpressBus hub
which can be either powered or not, I generally use it unpowered (I have
enough wires running over my desk already thanks!). But the problem I've
noted with that is that if I plug in certain devices together the power
drain is too high and the link lights all go off. Power it and it's fine. I
have a keyspan serial apapter too, I thing they draw a fair bit of power.
Your printer shouldn't since it presumably has it's own power supply!
Another very odd effect I've noticed is that I have a SIIG USB PCMCIA and
SmartMedia reader. It works fine but *only* if it's plugged in via the hub.
Why? I have no idea.
While I'm talking about USB I might as well mention a problem I've found.
I also have a LaCie monitor, which has two video inputs and two upstream
USB ports and the downstream USB ports. The idea is that you plug your
devices into the monitor, plug the monitor's upstream ports into two
computers, and connect the two video inputs. Then by switching the video
input using a button on the front of the monitor you can switch the video,
and all USB devices from one machine to the other.
The rest of my set up is a B&W G3 Mac and a x86 Linux box on the other
side. The G3 runs either MacOS or YellowDog. Now, this is all great. I boot
the Mac, the monitor sees the video and USB and switches to that
automatically. Then I boot the x86 Linux box. It comes up fine apart from
the fact it complains it has no keyboard until I switch over to it! But
from there is boots fine.
I can then switch back and forth and the keyboard and mouse connect and
disconnect from the two machines fine. It takes a few seconds each time I
switch for the keyboard to start responding, but that's ok.
Now, when I boot into YellowDog I can switch fine, and there is no delay in
the keyboard response when I switch back to the Mac which is great. What's
not so great is that every now and again the whole thing falls over. That
is, I lose keyboard and mouse input, but when I switch back to the x86
machine I can't even telnet or see the webserver on the Mac. Which makes me
think something has crashed in the kernel (yikes).
I'm running kernel 2.2.14pre19-rev1. Has anyone else seen this problem? My
guess is that it's a problem of connecting and disconnecting USB devices. I
assume the monitor just disconnects the link to the Mac when I switch to
the PC, so to the Mac it looks as if I've just pulled the keyboard out.
When I switch back I guess it looks like I've just plugged it back in. So
the other question is has anyone had problems when the hot-swap USB devices
at all?
Cheers
Pete
-- Peter M. Bagnall pete@surfaceeffect.com - http://www.surfaceeffect.com/
This archive was generated by hypermail 2a24 : Sat Aug 19 2000 - 12:06:43 MDT