Re: Lessdisks, LTSP, workstations, VNC, NoMachine NX, FreeNX (Was: Workstation Maintainance?)

[Jonas Smedegaard <dr@jones.dk>]

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On 02-11-2004 17:23, Finn-Arne Johansen wrote:

> Workstations - where people work with Mozilla and OpenOffice and such
>   applications
> Multimedia Workstations - where people work with scanners, image
>   manipulations, music, films and such
[cut]
> workstation - Actually this is more like a Multimedia workstation,
>   because everything is installed, and since we dont care about the
>   license cost why bother to diffrentiate?

I have had the situation of unequal hardware for workstations: Some
machines are great for some tasks, but too slow for other tasks.

Not installing slow tasks on slow machines is the simplest way to help
teachers and students choose the proper machines for a task.


> Thin-client-server - basically a combination of workstation, Terminal
>   server and a boot-server

For the large setups some of you aim at, I'd recommend the possibility
to setup a pool of application servers different from boot servers.

Or how well do Skolelinux setup multiple DHCP servers on same subnet?


> Lessdisks - Something quite similar to LTSP, but uses debian packages
[cut]
>   I have estimated somewhere between
>   200-400 hours to get a working solution with debian-edu.

Using Vagrant's 0.6.x or the package in Debian?


> FAI - well here I'm blank. I know Kurt loves it. I know it is really
>   fast in setting up new machines, and I know it supports LVM, which
>   systemimager does not. But I dont think it's usefull for updating old
>   installations. I know someone has said so, but I'm not sure. but
>   anyway, installing overagin on normal workstations should not be a
>   problem. 

Well, FAI is somewhere between lessdisks, preseeding and systemimager.
The author (last I checked) uses it to initialize a cluster. If you sit
down and spend some time tweaking the rules (clever mix of system
variables, shell scripts, CFEngine and replacement files) you can have
FAI auto-install whatever: Skolelinux machines, Skolelinux machines
tweaked to use FreeNX, Lessdisks and SDM, Skolelinux in hebraic (as I
assume that would require some tweaking).

Setting up FAI requires knowledge of diskless booting and of automation
with CFEngine and similar meta-scripting, so is not for ordinary school
teachers, but Skolelinux developers may find it ok. The core of FAI is
itself a diskless setup - each client boots into the diskless core, and
(normally, but everything(!) can be tweaked in FAI) the local harddrive
is initialized and a system automatically installed and tweaked locally.

So, if, as you described, you have 5 laptops of different brands but
luckily can use exact same configuration (crossing fingers at each
upgrade) then FAI is not for you.

If you, on the other hand, have 40 machines, some of which you may not
even know about at first, and you can't trust your luck in simply
distributing an equal snapshot, then FAI is certainly for you.


> On servers, I prefer to have cronjobb running, with the following tasks 
>   apt-get -qq update
>   apt-get -qq autoclean 
>   apt-get -qydu dist-upgrade
> That way I get an email from the server telling me what should be
> updated, and which server it comes from (okay, I've added som logic to
> this one...)

Sounds exactly like cron-apt?


> Peter Reinholdsen has mentioned dsh, and in fact dsh is distributed on
> our server profile.

Wauw, looks interesting. A related one is clusterssh, but this sounds
far more advanced and flexible!


> These workstations could do everything that dont need a huge swap disk.
> given that you have enough memory. In fact, lessdisks could be used for
> that as well, but lessdisks (as of today) needs a local disk for swap. 

No it does not. Compile a Linux kernel with support for NBD, GNBD or
ENBD, and configure it according to the (I assume) simple guidelines in
the relevant README.Debian.

Security updates then involves taking the new Debian-packaged Linux
kernel and patch with the (maybe updated) Debian-packaged xNBD kernel
patch, and produce a new binary kernel package for distribution with the
usual APT channels.

Sure, swap over the network is not supported by default. If you want
Debian to support that, then convince the relevant package maintainers
to include your favorite xNBD patch with the official kernels - or maybe
convince someone to maintaine noew xNBD-enabled kernels (perhaps the FAI
maintainer, who seem to like maintaining parallel kernels).


Or even better: Investigate if any of the xNBD patches are in fact
possible to isolate as independent compilable kernel modules. Then you
won't need to maintain a kernel, just a module.


Similar for your favorite webcam or touch-screen kernel module :-)


> Some of the documentation for FAI indicates that it might be used as
> diskless setup as well.

In theory you can adapt the FAI core to be used for diskless operation
for thin clients, but I wouldn't bet on that. Lessdisks prepares a core
for use by end users - FAI prepares a core for its own "development
environment" to automagically tweak remote machines.


> I also forgot why I put in VNC in the subject line, but ....

You probably intended to describe it next to FreeNX: It should only take
few hours to make an otherwise working lessdisks setup use either FreeNX
or VNC, provided those technologies were properly packaged for Debian
already.

FreeNX is off course the most potent of the two, but also the least
tested (hey - it isn't yet in Debian, so in some sense vaporware).

 - Jonas

- --
* Jonas Smedegaard - idealist og Internet-arkitekt
* Tlf.: +45 40843136  Website: http://dr.jones.dk/

 - Enden er nær: http://www.shibumi.org/eoti.htm
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