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

[Jonas Smedegaard <dr@jones.dk>]

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On 02-11-2004 22:28, Finn-Arne Johansen wrote:
> On Tue, Nov 02, 2004 at 08:01:04PM +0100, Jonas Smedegaard wrote:

>>>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.
> 
> 
> Well, slow machines should be used as Thin Clients, or dumped. 

You wondered if non-multimedia workstations is relevant at all.

Some machines are fast enough even for streaming audio and video, but
too slow for


>>>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?
> 
> 
> Jonas, have you actually looked at what SKolelinux are ? No, we dont
> set up multiple DHCP-server on the same subnet, we uses one dhcp-server
> on the backbone, and one for each of the thin client network, and let
> the one application-server for each of the thin-client network act as
> application-servers.

Yes, I believe I know what Skolelinux is.

And as I wrote, some setups may be better off using multiple application
servers than one huge catch-all server. Personally I'd rather that a
hardware failure causes my setup to run on 3/4 horse power than being
completely down.

How would you setup multiple application servers for same subnet using
Skolelinux?


>>>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?
> 
> 
> This estimate was in august , with what was availible then, Now with
> Vagrant's 0.6.x package the estimate is maybe a bot more accurate,
> around 270-300, but not including the 50+ hours I have, already put in
> to the project. 

Hmm - I still do not understand the time count procedures. Should I
include the time spent packaging lessdisks if I was to do the math?
Should we include the time Vagrant puts into it?


>>>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).
> 
> 
> well as you may not have noticed, the aim of skolelinux is to do the
> tweaking in advance, so that the avarege teacher ar ecapable of setting
> up the network. 

I noticed.

As such I would rule out FAI for Skolelinux role-out. But I would
advertise FAI as a very very powerful development tool for Skolelinux
(and other CDDs aiming at fully automated installations): CFEngine rules
(or new tasks, or whatever) can easily be tested in full-blown
installations, and by changing a single variable the whole lot can be
tested for a different target (like testing localization-config for both
woody and sarge).


>>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.
> 
> 
> Well I have a solution on my mind for tweaking the customization for
> each type of laptop as well with systemimager, and still use the same
> image. 

Globally distributable tweaks, or just for your personal hacking
convenience and pleasure?

FAI configuration logic is to divide tweaking rules into logical groups.
Such ruleset can be distributed similar to autoconf-archive.

I know Holger Levsen in Germany is working on this.


>>>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?
> 
> 
> Well, There is a slightøy difference in the resulting email, where
> cron-apt reports "something went wrong with the last update", i get an
> email telling me that "you have to upgrade xpdf, telnetd and friends"

Ok. I don't know cron-apt myself (sorry, I didn't make that clear).


>>>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.
> 
> 
> But then we have to maintain our own kernels, or at least not use the
> kernel that comes with the solution. But yes, I know how to build a
> kernel, and I have actually built 4 or 5 of the kernels for Skolelinux,
> due to lack of security patched kernels from Debian. 

I don't quite get you there. Do you tell me that LTSP so far have
provided kernel updates "with the solution", readily packaged for 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.
> 
> 
> Which we would like to avoid. 

Me too. But rather that than having to deal with kernels from less
trusted sources!


>>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.
> 
> 
> That could be a solution. 

OpenAFS is one such module. It is possible to _not_ use local caching
(or only RAM-based caching).


>>>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.
> 
> 
> Well, after I have tested FreeNX for some time, I would not use VNC as
> a replacement. 

No no, but opposite: Use VNC (which is well-known, well-tested and
documented), and replace with FreeNX when production-ready.


>>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).
> 
> 
> Well some would rather have NoMachine NX, which would never make it
> into the debian-archives. 

Then you just make a special agreement like with Opera and SUN Java, right?


 - 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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