Sorry, for the long subject, but I feel some need to clarify some thoughts.
Lately there has been much talk about workstations and diskless and thin client setups. I'm not the developer behind thos different solutions, but because of my employment in the department of education in Oslo (the cpital of Norway) and my involvement in creating a working Sarge-based Debian-edu, I have looked at different solutions in optimizing the workstations in Debian-edu. To simply, the picture, I think we have 7 basic types of installations: Main servers - giving basic services such as authentication, home directories, printing, email, dns, dhcp and others Terminal servers - Giving thin clients the possibility to run applications such as mozilla an OpenOffice Boot servers - Giving diskless machines a kernel and a root filesystem Workstations - where people work with Mozilla and OpenOffice and such applications Multimedia Workstations - where people work with scanners, image manipulations, music, films and such Thin Clients - Workstations that boot off boot-servers, and where they work on a terminal-server Laptops - Where people can take a working solution and bring it home, without the need for a connection to the main-servers. In Skolelinux we have main - a main-server with all the services (it's hard to spilt them) 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? Thin-client-server - basically a combination of workstation, Terminal server and a boot-server Standalone - some would call this a bastard, but it works for laptops, but do you really want to run woody with kde 2.2 on a laptop? Thin clients comes when network booting from the Thin-client-server, so we've got that covered as well. Then some "Products": LTSP - The solution used to set up thin clients in Skolelinux. In our case the boot server and the Terminal server is the same, and filesystem for the thin clients are exported using nfs. LTSP 3 was built by taking pieces from various distros, mostly from RH6.2, and creating a root file system of it. LTSP 4 is built from sources, using its own build environment, where you need 2 GB of sources, and a total of 5 GB disk to build, and you have to be root while building. (not even sure if sudo will do, fakeroot is not enough) Lessdisks - Something quite similar to LTSP, but uses debian packages to create the root filesystem. Maybe a bit larger filesystem is exported, and not so optimized libraries, but a lot easier to upgrade. security patches the debian-way. while lessdisks are in fact a thin-client solution today, I have done a proof of concept, using some hours, to create a diskless setup with lessdisks using recycled PC with PIII 500MHz with 128 MB memory as workstations, and an old PII 266MHz Toshiba laptop with one PCMCIA-nic and one usb-nic as a server. No problem at all watching video in avi format, or running flash applications in mozilla. I have estimated somewhere between 200-400 hours to get a working solution with debian-edu. where we use lessdisks to create diskless workstations capable of running as normal workstations (not multimedia workstations where you edit huge images, edit video or sound, but capable of running flash and java and stuff). This will make way for boot servers that may server more thin clients with less memory/cpu. FreeNX - A Citrix/ICA like technology for Linux. not a replacement for LTSP or lessdisks, but more an enhancment. With NX, you may run the application server on the other end of an old modem line, and you may still run applications like OpenOffice and Mozilla on top of KDE, and get a workable solution. But dont you dare to run multimedia-applications on top of that. Then you will need more bandwidth. Actually I've watched videos over my DSL line with this, but without sound. It should also be possible also be possible to get sound working, and to get file and print over samba to work, but I have not succeded. You may need NoMachine NX for that. NoMachine NX - The commercial part of NX, and the origin of NX. You may buy support from them. I suspect that it may be easier to set up file/print/sound sharing using NoMachineNX. They are really nice people to talk with. Systemimager - This makes it possible to create images for installing on many machines. It also makes upgrades on many workstations easier, we are already using this on ~100 laptops on Ulsrud, where the laptops may be upgraded automaticly whenever they are started each day. (we dont upgrade them each day of course) For more info, please look at: http://developer.skolelinux.no/dokumentasjon/installing_SL_to_a_laptop.txt http://skolelinux.no/~finnarne/debian-edu-sysimg/README.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. Then lets look at different techniques to maintain the various installation of skolelinux-machine-profiles. I like to diffrentiate between servers and workstations/laptops. 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...) Then I might log in to the server, and do the upgrade manually, I used to have my own server on which I upgraded things first, and then checked, but now that server(s) is busy working with something else. But on the other hand, we dont play around with our packages that much, so basically, things should be safe. The laptops I've set up, is set up using systemimager, and yes, although we are doing 5 or 6 different laptop types, all with different soundcard, nic (both wire and wireless), graphic cards and cpu flavour, We are using the same image on all of them. What we do is that we create an image, then install on all the others. THen we take one of the laptops, and upgrades that one, check that things are okay, and then upgrades the rest the next morning when the students log in. Depending on the number of workstations, I would either used the server model (if this was the one machine that had all extras like scanner, videokamera, ++) and do the upgrade manually, or if this was a classrom full of workstations, I would have used the model we uses for laptops. But instead of upgrading whenever the machine gets turned on, I would have a cron-job checking for upgrades each morning or something. Peter Reinholdsen has mentioned dsh, and in fact dsh is distributed on our server profile. But I'm not sure how much dsh is in use. I have searched the net for a description on how to use it, and found something like: first do the upgrade on one machine then copy /var/cache/config.dat to every other machine then run apt-get upgrade through dsh on the other machines, and debconf has already gotten all the answers. You might need to make sure that debconf only asks unseen questions. And I guess you need to have identically setups/machines. Okay, what about diskless installations, using FAI or lessdisks or LTSP? When it comes to LTSP, I feel that while LTSP has proven quite capable of things, it will still only remain a thin client solution. I know NoMachine has a setup where they uses LTSP, and I know that LTSP know supports rdesktop, I feel that LTSP is not capable of running applications like OpenOffice and Mozilla locally. Well, It's capable, but I dont want to have the responibility of security patching thos apps. When it comes to diskless workstations running OpenOffice, Mozilla and KDE locally, I would rather use lessdisks, As I have no experience with FAI, but I think it could be used. 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. Some of the documentation for FAI indicates that it might be used as diskless setup as well. Disclaimer This email has gotten so long that I forgot why I started it. I also forgot why I put in VNC in the subject line, but .... I started this email this morning, and kind of finished now. I guess I'll be back with more when I remember why I started this. But if I kill this email now, I will regret it later /Disclaimer -- Finn-Arne Johansen [EMAIL PROTECTED] http://bzz.no/
