update minimum RAM info (LTSP diskless clients be switched to thin clients on startup, if RAM is less than 320 MiB)
update number of workstations / LTSP servers; add info regarding LTSP subnets.
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| * You can have up to 50 (diskless) workstations on the main network.
* You can have up to 20 LTSP servers on the main network.
| * You can have hundreds of workstations on the main network.
* You can have a lot of LTSP servers on the main network; two different subnets are preconfigured in LDAP.
There are different ways of setting up a Skolelinux solution. It can be installed on just one standalone PC, or as a region-wide solution at many schools operated centrally. This flexibility makes a huge difference to the configuration of network components, servers and client machines.
The purpose of the different profiles is explained in the network architecture chapter.
- The computers running Debian Edu / Skolelinux must have either i386 or amd64 processors.
- Thin client servers need two network cards when using the default network architecture:
- eth0 is connected to the main network (10.0.0.0/8),
- eth1 is used for serving the thin-clients (192.168.0.0/24) .
- Consider 2 GB RAM for 30 clients and 4 GB RAM for 50-60 clients.
- Disk space requirements depend on profiles used, but any disk larger than 25 GiB will be sufficient for a workstation or standalone installation, 30 Gib for a thin-client server and at least 40 GiB on the main server. As usual with disk space on a main-server, it's "the bigger the better".
- Thin clients can run on as low as 64 MiB RAM and 133 MHz processor, though 128 MiB RAM and somewhat faster processors are recommended.
For running Iceweasel/Firefox and OpenOffice.org, 128 MiB RAM is a minimum requirement.
- For workstations, diskless workstations and standalone PCs, 800 MHz, 320 MiB RAM are minimum requirements, though 512 or 1024 MiB RAM will perform considerably better. Just a faster CPU will speed things up.
Swapping over the network is automatically enabled; the swap size is 32 MiB, and if you need more you can tune this by editing /etc/ltsp/nbdswapd.conf on tjener to set the SIZE variable. Please tune up the swap size either locally on the PC or on the server.
- If your diskless workstations have hard drives, it is recommended to use them for swap as it is a lot faster than network swapping.
On workstations with little RAM the spell checker can cause OpenOffice.org to hang if the swap space is too small. Then the system administrator has to disable the spell checker on OpenOffice.org or students have to kill OpenOffice.org, resulting in loss of work. Enabling at least 512 MiB swap on a 320 MiB RAM workstation solves this, and the spell checker runs smoothly.
- Laptops have the same requirements as for workstations since they are just movable workstations.
Hardware known to work
A list of tested hardware is provided at http://wiki.debian.org/DebianEdu/Hardware/ . This list is not nearly complete
http://wiki.debian.org/InstallingDebianOn is an effort to document how to install, configure and use Debian on some specific hardware, allowing potential buyers to know if that hardware is supported and existing owners to know how get the best out of that hardware.
An excellent database of hardware supported by Debian is online at http://kmuto.jp/debian/hcl/.
Requirements for network setup
When using the default network architecture, these rules apply:
- You need exactly one main server, the tjener.
- You can have hundreds of workstations on the main network.
- You can have a lot of LTSP servers on the main network; two different subnets are preconfigured in LDAP.
- You can have hundreds of thin clients and/or diskless workstations on each LTSP server network.
- You can have hundreds of other machines which will have dynamic IP addresses assigned.
- For access to the Internet you need a router/gateway (see below).
A router/gateway, connected to the Internet on the external interface and running on the IP address 10.0.0.1 with netmask 255.0.0.0 on the internal interface, is needed to connect to the Internet.
The router should not run a DHCP server, it can run a DNS server, though this is not needed and will not be used.
If you need something for an embedded router or accesspoint we recommend using OpenWRT, though of course you can also use the original firmware. Using the original firmware is easier; using OpenWRT gives you more choices and control. Check the OpenWRT webpages for a list of supported hardware.
It is possible to use a different network setup (there is a documented procedure to do this), but if you are not forced to do this by an existing network infrastructure, we recommend against doing so and recommend you stay with the default network architecture.