Mandag 3. februar 2014 22.27.09 skrev Franklin Weng: > So can I conclude that, for *every* school you administrate, there would > be - a main server, running > * LDAP service, for user account management > * X server so that thin client can connect to > * And anything else? > - an LTSP server, so that you can diagnose and solve issues remotely
Yes. One server serving different network clients[1] from thin clients (LTSP), low fat clients (= diskless clients), remote desktops or roaming workstations[2]. The roaming workstation which allow you to log directly into the schools network when the machine is attached to it by wire or wifi. And it can be used outside the schools network without any hassle. 1. https://wiki.debian.org/DebianEdu/Documentation/Wheezy/HowTo/NetworkClients 2. https://wiki.debian.org/DebianEdu/Documentation/Wheezy/Installation#The_installation_process > And many thin client machines which would get remote X desktop It depends on the network bandwidth and the number of concurrent clients. Traditionally running 30-50 thin clients on a 100 Mbit/s switched network (with full switch capacity) are doable because each thin client are using ~2 Mbit/s of the bandwith. Some municipalities has been running 70 thin clients on 100 Mbit/s network because at max 60-66 percent of the machines are in concurrent use. With 1 Gbit/s thou, a you might serve even more thin clients. That said, there are other limitations regarding saturation. This is a situation which happens when running fancy flash animations or video- streaming on thin clients. Then the bandwith might move up to 20-30 Mbit/s on each client. Then it's only doable to run 4-5 concurrent clients. Back in 2002-2003 we got a lot of heat from Microsoft loyalist who claimed that thin client was bad on Linux, and remote desktop was better, even if the video-situation is even worse on remote desktop protocols as RDP or Citrix. Several persons had already an solution to this by providing low fat clients where all the software runs on the client, where all the files are stored on the main server. There are several pluses with this setup. With lowfat clients you run video on the local PC, not having to do pixel pushing from the server to the client, saturating the network. The client are still stateless as thin clients, making it really scalable from a maintenance viewpoint. Maintaining as few disks as possible is what makes Debian Edu / Skolelinux really affordable to maintain. Secondly you can run 3x the number with lowfat clients compared to thin clients (LTSP) on a 10-100-1000 Mbit/s network. Thirdly with lowfat clients you can reduce the computer power on the server compared with LTSP because full usage of client computer power. Around 2005 it was possible to get reused computers with 1,5 GHz CPU. You can run a 300 MHz computer as thin LTSP client. But due to network saturation video an fancy flash animations are saturating the network. With 1,5 GHz single core CPUs or better, video, flash and other things runs just fine on lowfat clients. 512 MB RAM works with lowfat clients. But I'll recomend 1 GB RAM. You should allow local swap. For thin clients I would recomend 256 MB RAM, and not the minimum requirement which are documented in the user manual. End user software are beefed up with more features and nice graphics for several years. Going for a little more RAM on the client side are a small investment, and still much lower compared to what's expected when running proprietary software on similar hardware. Just for giving you some standard numbers: Standard recommendation for Windows 7 are 4 GB RAM an dual core at the minimum, for real life office usage. Often 8 GB RAM is standard. The minimum requirements promoted by Microsoft renders your machine useless in waiting for something to happen. This is how netbooks were killed where the requirement was 1 GB RAM, and you could not run a youtube video with a powerpoint presentation without waiting for several minutes. On Linux everything works even smoother with 512 MB RAM. Windows 8 requires even more computer power in real life usage, especially on the graphic chip (GPU). This due to the extensive pixel moving with tiles. Main+LTSP-server on one main workhorse machine might need a dual core 3 GHz CPU + preferably 8 GB RAM (several schools runs fine with 4 GB). Lowfat clients you can nicely run on a single core CPU with preferably 2 GB RAM (many open files with many concurrent users needs a little-bit more memory). > Is that true? Please correct me if anything wrong. > > For the main server, how powerful would it need to be? We've got a summary of the minimum requirements here[3]: 3. https://wiki.debian.org/DebianEdu/Documentation/Wheezy/Requirements > In Taiwan, we use DRBL and Clonezilla (http://drbl.sourceforge.net/) but > we use it to deploy a *real* system to remote PCs instead of just a > thin client. Seems to be a good combination. The different client types in Debian Edu are made over time to be get maximum user experience depending on network throughput and client types expected in a modern computer network. More client options makes it easier for you to make the most optimum choice without loosing functionality. > Furthermore, do you have any documentations describing how LDAP server > needs to be set, and how clients needs to be set so that user accounts > management can be done this way? There are not much to say about LDAP since it's preconfigured as a part of GOsa. Please consult the Getting Started[4] part of the manual: 4. https://wiki.debian.org/DebianEdu/Documentation/Wheezy/GettingStarted That said, if you want to re-configure the LDAP to another network setup, you need to do considerable more configuration engineering involving Kerberos, LDAP and GOsa to get it up running. I don't think this part on LDAP in the documentation are really updated yet, but I found this in the general documentation[5]: 5. https://wiki.debian.org/DebianEdu/Documentation/Wheezy/HowTo/NetworkClients#LTSP_client_configuration_in_LDAP_.28and_lts.conf.29 Best regards Knut Yrvin -- President -- Fri programvare i skolen (Free Software In Schools) Please participate in making free software for schools mob: + 47 934 79 561 -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected] Archive: http://lists.debian.org/2074424.LFEmqMIVfo@hjemme-pc
