[K12OSN] Re: How Low can you go?

pogson robert.pogson at gmail.com
Mon Jul 10 20:51:17 UTC 2006

        Does anybody have experience with using it with just a few
        computers that
        could share?

Because the typical desktop user is clicking and viewing, and
occasionally loading something, the load on AMD64 3000 is about 3%
average per user, that is about 90 MHz per user. Allowing a margin for
64 bitness, you should be OK with as little as 100 MHz per user. Because
you have so few clients, you probably need a factor more, because the
load will be variable. That is, it is quite probable that all three are
active at once. 1 gHz should be useful for three. Where you cannot be
short is RAM. You must not swap so you want 256 to 512 MB for the OS and
services and 50 MB per client so you could likely get away with 512 MB
for three clients and you need a few hundred MB for file caching. I have
had thirty clients on 1.5 gB.

My advice would be to splurge on a new server, one of the barebones
minimalist things. I have seen AMD64 3200, 512 MB, gigabit, case, PSU,
no hard drive or OS for as low as $400 on speicals.e.g.
http://www.ncix.com/products/index.php?sku=18419  at CDN$329.  One of
those would make a great server and you could use a bunch of P3s as thin
clients. Steal their hard drives and a CD drive for the server. You do
not need viedo card, keyboard, monitor or mouse on the server after
installation, so you can borrow those and administer the beast from one
of the clients. The advantages of this route is more snap on the desktop
and expandability. If you do expand, get a switch with at least one
gigabit/s port for the server, e.g. ASUS GIGAX1024P Smart 24-PORT
10/100MBPS + 2-PORT 1000MBPS Managed RACK-MOUNT Switch These are cheap
but effective.

Another low cost approach would be to use the thin clients as a cluster
server with clients on top. An example is OpenMosix + LTSP, which would
share spare cycles from one machine to another by shifting processes. At
100 mb/s that would not be snappy. You might help by adding gigabit
networking, but I am not sure that the result would be worthwhile. Many
desktop apps and servers share memory among processes and these do not
migrate. OpenMosix with MigSHM does that, but migration is overhead. I
am not convinced the extra configuration work would justify the
performance with slow nodes.
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