[Gllug] The netwroked house - a terminal in every room >;)

[John Edwards]

On Mon, Mar 07, 2005 at 06:12:23PM +0000, M.Blackmore wrote:
<snip cabling> 
> But to the "terminals". Rather than sink money into a number of new 
> personal computers, the idea would be to sink money once into a recent 
> (but second hand preferably) powerful server. The only reason to run 
> windows is on a machine or two for the kids to play games upon, which I 
> will confine to the kitchen or similar so I can keep an eye on them. I 
> also want to restrict their ability to browse sites unsupervised, but 
> that is another issue for now though will become more pressing to find a 
> vetted access to websites, like what the schools use.
> 
> How should I go about doing this server/terminal system?
> 
> One option is to use a number - 3 or 4 I think -  400-500mhz 
> motherboards around, with enough atx cases for them, and enough ram for 
> 256-384mb ram for those, more if I denude the grownups PC's of a couple 
> of 128mb sticks. Though the cases are large, clunky and not exactly 
> quiet. Could do for the kids' "playroom" for example.
> 
> Can these be pressed into service? I'll have to invest in some new 
> monitors as there are none associated with these, all being boards left 
> over from upgrades, and cases from long dead atx format p133 era machines.
> 
> Or should I invest in some new or second hand dedicated "terminals"? If 
> so, what? ( Or mini-ITX 'pooters? If so, what specs?
> 
> What is the relationship in serving up x sessions to a fairly dumb box, 
> i.e between the speed with which screens will be drawn and perceptions 
> of "fast" and "slow" on the user end, between the server in t'loft, and 
> the speed of the terminal - a 500mhz board with say 384 ram. Or for a 
> mini-ITX probably faster and a bit more ram. What is the relationship 
> between the video output on the terminal in terms of its "card" and 
> itsspeed, compared to the power of the server?
<snip> 

Hi
There are several HOWTO that deal with X terminals and XDM on 
www.tldp.org, but here's a quick summary of my experiences. I 
use the term "server" for a machine to which a terminal connects, 
and not for the "X server" program.


_Server for X terminals_

Lots of RAM. 512MB could be enough for about 4 machines running 
a small window manager and a GUI program. It you use larger 
programs such as Gnome/KDE and Firefox then you will need more.

A CPU faster than 500MHz would be recommended if your users don't 
want the occasional slow down if more than one person is using it.

If you don't have fast drives then you could try using multiple 
hard drives on their own IDE channels instead. The root parition 
and "/usr" goes on one and the home partitions on the others.
Alternatively if you have several fast drives than try RAID5.

100Mbit/s network is a must. Avoid cheap network cards for the server.

As for software, you need to start a X Display Manger (xdm, gdm, etc) 
with xdmcp enabled in it's configuration file, and with some you may 
need to explicitly allow access from a set of IP addresses.

Encrypting the traffic is not easy unless you tunnel with SSH, which 
will require much more powerful CPUs on both server and terminals.

You'll also need to consider whether to use the server or terminals 
for the fonts. If you use additional fonts then it maybe easier to 
install them on the server, and configure xfs on the server to listen 
on TCP. Then you edit the XF86Config on the terminals to use that 
instead of the local fonts.


_X Terminals_

You can use an average desktop with a small hard drive for the terminal.

Beyond a Pentium CPU, I've not noticed much improvements for a fast
CPU unless your display is continously changing (eg watching a video).

A reasonable system would have 4MB video card, and minimum 32MB RAM.

Transtec (www.transtec.co.uk) sell a Linux based Thin Clients for 
179+VAT. They come with 64MB, but if you need to use programs that 
are more graphics intense then you can easily remove it for another 
100MHz SODIMM.

For software I've used a cut down Debian install. Then start X from 
the inittab, and get it to connect to the server with something like:
	/usr/bin/X11/X :0 -query server-hostname


If you want to use Windows machines then alternatives could be to use 
VNC (either for Windows clients or a single Windows remote machine) or 
Cygwin's X server (on the Windows client).


-- 
#---------------------------------------------------------#
|       John Edwards    Email: John.Edwards at uk.com        |
|                                                         |
| A. Because it breaks the logical sequence of discussion |
| Q. Why is top posting bad ?                             |
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