Re: [seul-edu] How big a server?

[David Johnston <david@johnstons.net>]

Jan Hlavacek wrote:
> Hi everybody,
> I am sure there must be somebody out there who has done something
> similar and can give me some advice:
> 
> our college has several student labs running NTs. Our department
> (math) is currently the only department that uses Linux....
> Lately, our chemistry department contacted us asking for help
> setting up some sort of unix solution for their students.  One
> possible solution I found is using an x-server on the NT machines
> in the labs to login to one linux server....
> However, to actually be able to use this we will need powerful
> enough server to support many simultaneous connections. And this
> is wnat my question is:
> We may have several hundreds items in passwd file, and as much as
> 50 (usually not more than 25, but let's assume two classes working
> at the same time) users logged in at once.  The applications used
> would be some mathematical software (CAS of a sort, octave, maybe
> kseg or drgenius), molecular modelling software and some other
> computational chemistry stuff, so it may be kind of
> computationally intensive, but i wouldn't expect anything
> outrageus, these are undergraduate students.  Does
> somebody have any estimate about how big machine (memory, CPU)
> am I looking for?
> 

The molecular modelling software I've seen is very CPU intensive,
so I would be inclined towards a big server.  However, I have a
suggestion that may help.  I have been working with a local
school to set up 80 X servers that will run many lighter clients
on a single server (mostly Netscape).  In our tests, we found
that using Mosix to cluster two servers together significantly
improved response time.  I would consider building a small
cluster, perhaps four machines, and add more as needed.  We have
seen good results when adding older, slower machines to a
cluster; Mosix seems to look at the machine's load average, not
the number of processes, when determining which machine should
handle the next task.

-David
david@johnstons.net