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Re: [school-discuss] linux distributions for low resource computers,



OK, so $300 for a diskless workstation vs. $150 for thin clients.  It's
only 3 dB in cost increase I guess...and as long as the choice of diskless doesn't reduce the number of classroom PCs you can afford; we've found here in Atlanta that 2:1 is optimal given classroom electricity and space limitations, and even our 1:1 fifth grade classroom teachers have now asked to go back to 2:1 because they're tired of resetting the circuit breaker and they feel that 2:1 is adequate for the vast majority of their needs.

But I'd really like to know how many thin clients you can load up with Java games, YouTube, and 3d accelerated programs *before* a server bogs down, and as a function of the server specs (quad core single CPU all the way to Jim's monster servers). This could make a huge difference in the overall cost of the two solutions. If a currently available $500 classroom server can handle at least 10 clients doing graphically intensive activities all at the same time, then it's a comparison of $200 ($150 client plus $50/client server cost) per workstation to $300 per workstation. Worse, in 5 years when it's time to upgrade the school computers, you have to do it for all workstations, not just the servers. For our school with 400 workstations, that could be say $200/diskless node (assuming cost comes down while performance goes up) or $80,000 vs. replacing 40 servers at $500 each (no cost reduction, just performance improvement) or $20,000. Nope, I still think the thin client solution wins, it's just that you need more servers to do graphically intensive stuff.

Would like to read Robert A's post, but the link below doesn't work, can you correct and resend?

Best,
Daniel


Dean Montgomery wrote:
On June 3, 2008, James P. Kinney III wrote:
Can you provide some specs on the server you are using? My LTSP
servers are pretty beefy monsters (2-4 cores, 2-4 CPU's, 8+GB RAM,
multiple Gbit NICs, etc) that run 100-150 thin clients each.

That is in the ballpark that we have been using.  Spend money on the
server and save on the client.

With LTSP when we loaded up a lab of 30 students doing Java games,
youtube,  or trying to do any 3d accelerated programs the server and
the network would bog down.  Even powerpoint slide transitions are
choppy on LTSP.

With diskless once the java game (or google earth) is loaded, there
is no more network traffic.  A bonus is the kernel caches the program
in the client's ram so the next time openoffice or firefox is clicked
on, it starts almost instantly with very low network traffic.   We
can have 100+ kids and teachers doing a java game, youtube,
openoffice, or google earth without any performance issues.


I would expect for diskless clients the key factors will be
primarily network bandwidth followed by hard drive throughput.

That is why we do a gig connection from the server to the switch.
Hard drive is a RAID - kernel does some file caching so the drive
isn't thrashing.  Using sar I've noticed that the nightly backup is
the only time that the hard drive and CPU start pushing 100%.
Throughout the day they rarely reach 100%.

The main reason I have been avoiding the diskless format is heat
and the need for fans. A silent environment is a big plus from the
thin client format. Although I do have my hands on a new fanless
client from VIA (pico-format) that can be either diskless or thin
format.

Yes I agree.   We have been focusing on cost savings instead of noise
reduction.  The computers are quieter than fat clients but they still
have a CPU and Power fan.  AMD's Cool-n-quiet throttles it down even
more.


Here is a screenshot of a diskless desktop... http://www.sd73.bc.ca/misc/linux/sd73.png ... and yes all the
students can do this at the same time with no slow-downs or lags. : )
Think about it... the movie file is travelling over the network as
compressed avi and then is decrypted/displayed on the client
workstation.  Beryl is loaded into client RAM and doesn't require
much network IO.

Here is a screenshot from on the server running about 150 diskless
clients.  Notice the gkrellm monitor on the left showing 46% & 10%
cpu usage; bond0 is 2 bonded NICS. MEM is hardly being used. http://www.sd73.bc.ca/misc/linux/skss_charts.png

The rest of the screen shots are from sar and they show that the
biggest load on the server is during the nightly backups. http://www.sd73.bc.ca/misc/linux/

==== If you still don't believe me see what Robert Arkiletain says
about diskless.  (Robert wrote Teacher Tool for LTSP.)

<htp://groups.google.ca/group/bcfosss/browse_thread/thread/f4b51edeffdc1e56?hl=en>




--
Daniel Howard
President and CEO
Georgia Open Source Education Foundation