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

[Finn-Arne Johansen <faj@bzz.no>]

On Tue, Nov 02, 2004 at 08:01:04PM +0100, Jonas Smedegaard wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> 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.

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

> > 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.

> > 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. 

> > 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. 

> 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. 

> 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?

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"

> > 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.

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. 

> 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. 

> 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. 

> > 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.

That was my impression. I still think I have to look into this at some
point.

> > 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. 

> 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. 

-- 
Finn-Arne Johansen 
faj@bzz.no
http://bzz.no/