[ale] New Twiki topic LinuxInGASchools

[Jeff Hubbs]

If you had a round-robin DNS or something akin to TurboLinux Cluster
Server (about $2K last I checked), that's one way to go.  The thing is,
though, you're talking about engaging several machines to run several
instances of apps which, if run all on the same machine, might actually
make use of shared memory (my LTSP rig running Mozilla more than once
suggested this).  Consider further that many instances of the same app
run on a single system receives even more benefit from L1/L2 cache. 
This might be something to keep in mind as regards using separate app
servers; if you wanted to take this to the extreme performance-wise, run
your major app and only that app on a single server so that its L1 and
L2 caches stay as full of that app's image as possible and doesn't get
pushed out by anything else (granted, kernel, X, kdm, and whatnot will
do that some).

I may be wrong, but I don't think this is a very good use of the MOSIX
model.  Consider that CPU usage for most desktop apps is very bursty and
therefore running many instances of such apps tends to not hurt very
much because the bursts interleave with very little instance-to-instance
impact.  I know that some have tried to use MOSIX to make a Web server
cluster but I'm unclear as to how that's supposed to work without making
the "home node" work too hard.

MOSIX, to me, is best thought of as a "batch engine" that works with
"fire-and-forget"-type processes.  A good example would be a compile
farm; execute a "make -j" on the main node and stand WAY back.

- Jeff

On Mon, 2002-08-12 at 18:48, Dow Hurst wrote:
> Geoffrey mentioned the cluster thing as a way to beef up the LTSP 
> server.  Hows about that!
> dow
> 
> 
> Jeff Hubbs wrote:
> 
> >Just some idle notes and thoughts...
> >
> >On Mon, 2002-08-12 at 10:51, Dow Hurst wrote:
> ><snip>
> >  
> >
> >>Some of the ideas we tossed around were:
> >>Start small with a testbed situation such as setting up a local church 
> >>with LTSP using free hardware as our first learning experience.
> >>    
> >>
> >
> >Target churches that operate preschools.  My daughter went to Sandy
> >Springs United Methodist Preschool and they did/do get a number of
> >donated machines of fairly advanced age.  Similar churches may well have
> >similar piles of hardware.
> >
> >  
> >
> >>Focus on LTSP as a leverage for old hardware.
> >>    
> >>
> >
> >Yeah!  LTSP, if nothing else, can be used as a study case for a more
> >elegant solution or it can be implemented as-is with modifications; I
> >took a shot at getting LTSP to work (diskless P/90 client) and found
> >that any KDE user can shut down the server (a non-starter, for sure!).
> >
> ><snip>
> >
> >  
> >
> >>Recognize the installed base of hardware in schools would not 
> >>necessarily change so the proposals have to account for this.
> >>    
> >>
> >
> >Quite true.  It seems as though there are Macs and Wintel entrenched,
> >and the level of machinery on hand runs the gamut.  The sticking point
> >is going to be creating useful server hardware, but it's pretty clear
> >that the range of PCs that people are casting off for being too slow for
> >use with Win2K and WinXP are the ones that begin to make good servers.
> >
> >R.D. Head Elementary in Gwinnett County is positively crawling with IBM
> >PS/2 300GLs.  They are PII machines, ~350-400MHz, with built-in video
> >and Ethernet.  I've worked with these machines before and I know that
> >they are positively horrible in Windows; one of my guys had one and it
> >would hang up every time he tried to copy a large file over the network,
> >and the video at high resolutions was oddly flickery.  I tried both
> >Win98SE and WinNT on another one and got similar results.  BUT, it ran
> >Linux very nicely - the video was just fine and the Ethernet was
> >flawless.  They have 300GLs at the Sandy Springs branch of the Fulton
> >County Public Library and they are murderously slow and crash-happy
> >under Windows and running IE.  However, for LTSP client, I estimate that
> >they're WAY overkill, but if they're all in place, then so be it - you
> >get your benefits elsewhere.  
> >
> >It's the server side - whether for LTSP or just file serving - where
> >things get tricky.  If it were me, I'd be interested in something,
> >anything, into which I can cram disk drives, whether IDE or SCSI or
> >both.  The idea is to get RAID going fully, such that you can lose any
> >one drive and still have a running machine.  RAM is also important
> >especially under LTSP.  You could find yourself running many instances
> >of the same app on an LTSP server, and while in some cases that's not as
> >huge a RAM load as you might imagine, in other cases it will be and if
> >you push the thing into a heavy swapping regime, all users will suffer
> >at the same time. 
> >
> >At least under LTSP, you CAN break up your app server requirements onto
> >multiple servers and in some cases this may be very desirable if the
> >nature of the network, disk I/O, or CPU activity for one app throws a
> >spanner into that of another app.  
> >
> >Any and all infrastructure hardware MUST MUST MUST go on a UPS.  THAT's
> >where the money that would go for MS licenses should go.
> >
> ><snip>
> >
> >  
> >
> >>Polish the project to perfection and sell it at the Board of Regents, 
> >>don't approach public schools at a low level due to entrenched 
> >>bureacracy and policies.
> >>    
> >>
> >
> >I very much agree; waste no time with anyone as low on the chain as a
> >principal.  
> >
> >  
> >
> >>Look into locating churches and private schools for testbed situations 
> >>we can leverage.
> >>    
> >>
> >
> >See above re SSUMP.
> >
> >  
> >
> >>Join with similar projects if possible and if applicable.
> >>
> >>    
> >>
> >
> >What's the story here, Linux client on Novell server and/or vice versa? 
> >I've done NT/Novell and Novell/NT, but not Linux with Novell.  
> >
> >  
> >
> >>Explore integrating Linux with Novell, or any other legacy OS or 
> >>hardware currently used in schools.
> >>    
> >>
> >
> >I have dealt with Linux/VMS interoperability, but I dunno if any schools
> >have any VAXen or Alphas running.  There may be little point.
> >
> >  
> >
> >>Really look into available educational Linux software and software 
> >>projects.  Recognize MS Windows won't go away due to educational 
> >>software currently used in schools unless we can find what is needed.
> >>    
> >>
> >
> >I feel that WinXX on the client side is inevitable.  Barring really
> >useful Linux software that justifies totally throwing a client over to
> >Linux, Linux' best use in the client role would be as a Web browser
> >platform, plain and simple.  This is also covered by LTSP deployments,
> >of course.  
> >
> >  
> >
> ><snip>
> >
> >At Head Elementary, I noticed that in the office, a splash screen for
> >SASIxp was visible.  You can read about this at
> >http://www.ncslearn.com/sasi/index.html.  I'd like to determine what, if
> >any, role Linux could play in reducing the deployment cost of that app.
> >
> >On another note, every time I see a giant stack of PCs of any age, I
> >want to build a massive cluster.  I don't think this would have any use
> >other than at the high-school level and even that would be specious -
> >you'd have to kind of write a lesson plan around it or just make it
> >available for the ubergeek kids to mess with - but it'd sure be cool.
> >
> >- Jeff
> >
> >
> >---
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> >
> >
> >  
> >



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