6 Dec
2009
6 Dec
'09
8:52 p.m.
On Sunday 06 December 2009, Patrick Shirkey wrote:
On 12/07/2009 05:36 AM, Gene Heskett wrote:
Whats a 'topic' Patrick? :)
ATM out of 6 mobo USB ports and 6 hubs making
branches as deep as 4
sub-hubs, I have only 7 open sockets. And I don't believe my usb map is
anywhere near a record setter.
Slightly off topic but...
I have had the pleasure of working with multiple usb
devices (in the
1000's) and I can say that I was able to get a 4 core, intel with 8GB
RAM to handle 500 devices at the same time with additonal pci->usb
cards. The only ones worth any time are made by Belkin. To stream data
to so many devices at one time you need a lot of available memory. 2GB
will handle about 100 devices nicely without sacrificing any transfer
speed.
A single USB 7 port hub can be made to chain 1x7 port hub-> 7 x 7 port
hub-> 1 x 4 port hub to give a total of 50 devices at one time. You can
modularise this chain to get 100 devices running off 1 usb bus. I have
my systems installed at La Louvre for instance where they are running
very well.
I had no chance to test latency for audio recording but from my
experience there are only two usb-2.0 chips on the market that get
anywhere near the 480Mb/s bandwidth available for usb-2.0 and they are
both used by Belkin.
And those chips ident themselves as?
My experience with usb cable lengths > 3 meters is
that they require a
booster.
Which is generally seen as a hub in an lsusb, they just don't socket out the
other 3 ports. I had 2 of the FDTI versions, but the far end wasn't exactly
on the same circuit, and a wandering lightning strike took one of them out,
so now I have a powered hub plugged into the remaining good extension cable
with 3 of its ports in use when an eldlerly coco3 is powered up, and that has
been working nicely for about a year now. All my usb-serial stuff is FDTI,
the pl2303 stuff is pure crap as we found on the heyu mailing list.
I'm glad to hear Belkin stuff is working well, but I'd almost expect that
since they had a heavy hand in the original USB specs. Too bad their UPS's
don't adhere to it.
Its also worth note that Belkin has a real and obnoxious screw you attitude
about linux over in the UPS division. They make, or relabel, a darned good
UPS, and it would be very nice if we could actually talk to it from linux.
Unforch, their latest monitor software, BullDog, was built on an RH-5.2
system, and turns into a 100% of all cores cpu hog on a 2.4 or 2.6 SMP
kernel.
Attempts to get them to rebuild it for newer linux's have been made,
including giving us the src so we can. Their return msgs will answer every
question with boilerplate, except about the BullDog software for linux, those
questions are trimmed from the replies and ignored. Obviously my next UPS
when these batteries have failed will have a label on it that is known linux
friendly, like APC.
Patrick Shirkey
Boost Hardware Ltd
--
Cheers, Gene
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