In order for ltsp to meet your needs it is necessary to prepare both hardware and software configuration. In this section we look at the hardware requirements.
The network is crucial and requires more attention using ltsp. In a typical ltsp setup several clients will be sending and receiving packets with the server(s).
1 – switch vs hub
Do not use a simple hub. When a packet is sent to a hub, all segments of the lan will see all packets. Traffic slows to a useless crawl. A switch, managed or unmanaged, however, keeps a record of the MAC addresses of all the devices connected to it. With this information, a switch can identify which system is sitting on which port. So when a frame is received, it knows exactly which port to send it to, without significantly increasing network response times. Unlike a hub, a 10/100Mbps switch will allocate a full 10/100Mbps to each of its ports. So regardless of the number of PCs transmitting, users will always have access to the maximum amount of bandwidth.
2 – 1000Mbps or gigabit (or greater) vs 100Mbps
If one has gigabit everywhere, i.e. all the clients and server(s) are all equipped with gigabit network cards, the switch has all gigabit ports, the router, ethernet wall points and rj45 jacks are all gigabit-rated and the cabling is category 5e or 6 (i.e. gigabit-rated) then there is no flow control issue and the bandwidth should suffice for small and medium ltsp usage. In larger setups with many clients then consider 10 gigabit-rated equipment instead.
This is what is recommended when planning a setup from scratch.
Otherwise using legacy hardware requires careful attention to certain details.
a – The router need only handle 100Mbps through its wired ports which is ample for most typical internet connections. Wireless is much slower which, while still able to deliver internet to non-ltsp devices is much more complicated trying to use it with ltsp.
b – A hub (see above) is not useful for ltsp.
c – The switch can be managed or unmanaged but (in most cases) should have at least one gigabit port for each server.
d - All pcs may have either uefi or legacy bios.
e – The server should have at least one gigabit (onboard or not) network interface. In simple cases where it is feasible to run everything within one subnet the server only needs the one network interface. Otherwise the server needs two interfaces to run a local area network or lan (separate from the router) containing the clients, and a wide area network or wan to run the subnet containing the router. The lan requires at least a gigabit network interface on the server whereas the wide area network or wan can manage with a 100Mbps network interface on the server.
f – Clients which have only 100Mbps (onboard or not) network interface are adequate and can be connected to 100Mb ps or gigabit ports on the switch. In either case, however, there arises the issue of flow control. Using the latest ltsp software resolves this issue.
g – Cabling and wall sockets may be only 100Mbps capable except for the connection from the gigabit device from the server to the gigabit port on the switch which all must be gigabit capable.
In addition to the above, legacy pc’s need further scrutiny.
i – A server’s hardware requirements are less severe with fat clients. The amount of ram memory is calculated: 2000 MB + 30 MB for each fat client it serves + 300 MB for each thin client. Examples: 10 fat clients only, 2300 MB of ram memory is the minimum but will do; 10 thin clients only, 5 GB is the minimum; 5 fat clients and 2 thin clients, 4.1 GB is the minimum. The recommended cpu benchmark rating (http://www.cpubenchmark.net/cpu_list.php) is similarly calculated: 2000 + 30 for each fat client + 300 for each thin client. Thus a 2300 rating is a minimum if running 10 fat clients only; a 5000 rating for 10 thin clients only; a 4100 rating for 5 fat and 2 thin clients. Of course these numbers represent the least amount acceptable.
ii – At the very least a fat client should have more than 1 GB ram memory (not SDRAM) but DDR, the newer the version, the better.) 2 GB is recommended. Its cpu benchmark rating is the most important. A rating of 1000 or more is recommended.
In general legacy pc’s which have similar characteristics are easier to setup and maintain. Otherwise variety requires more work.
iii – A thin client needs less memory but should have at least 256 MB. Otherwise the above remarks for fat clients apply.
iv – All clients may be diskless, uefi or legacy bios, 64 or 32 bit. Where these are similar there is less work for the administration.