Jaws slows down network transfers, a lot!

  • From: "Sina Bahram" <sbahram@xxxxxxxxx>
  • To: <programmingblind@xxxxxxxxxxxxx>
  • Date: Wed, 17 Sep 2008 10:48:36 -0400

Hi all,

I've tested this with jaws 9 and jaws 10 beta.

I'm on a gigabit connection with a very decent fast receiver on the other
side of my gigabit link. 1.8 terabytes of raid 5 15,000 rpm sass drives, so
on and so forth.

I want to transfer, let's say 50 gigabytes, from my laptop to the external
machine. I'm just using straight up samba for this, not the best protocol I
know, but it illustrates the point beautifully.

The specs on my machine are 7200 RPM 2.5 inch 250 gigabyte drive in a dell
e6400 laptop running the latest 2.8ghz core 2 duo processor and four gigs of
ram, etc, etc.

I'm trying to establish that hardware, is not the issue here, *smile*.


So I fire up the transfer, and it starts up at around 25 megabytes per
second. A rather pathetic speed, given the gigabit link, since it's only
using 20% of the wire, but it's acceptable, for now. I allow the transfer to
continue, of course, and it inches downwards, 24, 23, 20, 18, 15, 13 ... It
goes all the way down to around 7 mb/s ... At this point I'm not even at
more than 60% of a 100 mb/s connection, so much for gigabit.

I think to myself, there has got to be something wrong with the network, or
hard drives, or something ... This is utterly unacceptable. So I stop jaws,
and have a friend read the transfer speeds.

I not only climb back up, 15, 18, 20, 24, 25, but it keeps going, 28, 30,
35, 40, 45, 50 mb/s. I'm now at 400 megabits per second or 50 megabytes per
second over the network. This is now what I'm more used to seeing.

I fire jaws back up, ... 50, 40, 38, 35, 32, 28, and so on, all the way back
down.

What on Earth is going on?

The most I can think of is some interrupt being delayed or some event
blocking on something stupid jaws must be doing ... But wow.

Any ideas? It sucks to have to turn jaws off every time I want to do a file
transfer.

If folks think this is appropriate, feel free to forward to the jaws scripts
list or any other list.

In case my email gets lost in forwards, contact me at:

sbahram@xxxxxxxxx

Take care,
Sina

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