[WIN] Re: number of clients for WinVNC

[Ingecom - SERRE Jean-Christophe]

Joseph Delaney <jpd "at" TeachX.rutgers.edu> wrote:
>
> We are using WinVNC in a teaching lab, and have 20 Windows machines 
> and 5 Macs set to view a single WinVNC server (running Windows 98). 
> Most of the time this works acceptably if we keep the *total* number 
> of viewers under 20. Over 20 and I can almost guarantee a crash on 
> the server.
> 
> You can also feel the server slow down with each added connection, 
> and watching the screens on the viewers update can be kind of fun 
> (sort of like a pony race). Sometimes there is a lag of 30 seconds, 
> depending on what the instructor is doing, and there is no way that 
> it can keep up with lots of screen drawing, like in a powerpoint 
> slide show. But it works well enough for our purposes.
>
> On a related note, does anyone have any tips on fine-tuning this sort 
> of set up?

I think it would mainly be fine-tuning that W98 server -- there's a lot
of websites dedicated to everything you need to setup so as to get
acceptable performances from a Windoz: In System control panel,
Performances tab, configure typical use as "network server", set up a
fixed-size defragmented swapfile, all the usual stuff.

Also, you could tweak its TCP/IP registry settings, this solved
recurrent crashes on a W95 OSR2 fileserver for me. It is documented at:
  http://support.microsoft.com/support/kb/articles/q158/4/74.asp
The default "MaxConnections"=100 may be enough for you, but you can also
set to the maximum the "Size/Small/Medium/Large" network buffer option.

Last, you can apply the same tips provided for speeding up a single
connection: using the zlib-enabled server/viewer, restricting display to
8-bits, benchmarking encodings on your setup, remove fancy wallpaper...

>            Is there some way to set the multiple clients to use the 
> same connection so that the server is doing less work (only sending 
> out one screen update instead of 20?)

This would require hacking the sources for using broadcasting or
multicasting (unless there would exist some third-party tunnel tool
similar to SSH or Zebedee that could provide a broadcasting layer?).

Now, you could use daisy-chaining: Student-1 spies on Server, Student-2
spies on Student-1, Student-3 spies on Student-2...

OK, that's stupid :-) Seriously, you could set up a secondary "strong"
server that spies full-screen on your current server. Half of students
would connect to primary server, other half to the secondary one.

-- 
JCS - Jean-Christophe SERRE - INGECOM France - +33 (0)1.48.34.12.34

Les ordinateurs, c'est comme les galères,
pour aller plus vite il faut plus de RAM.

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