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Re: [K12OSN] Where is the bottleneck?

On 07/27/2010 08:20 PM, Christian Einfeldt wrote:

I have been supporting public schools w LTSP and LDAP for 6 years (about
to start the 7th year). For the first three years, we ran LTSP.  At the
beginning of the 4th year, we went to LDAP for exactly the reasons you
cite here, namely lagging across the network.  I am only a level one sys
admin (I'm actually a lawyer in my day job), but I'm pretty sure the
real sys admins chose LDAP because it was more efficient to push some of
the load onto the clients rather than have the dervers bear so much of
the brunt.

LDAP wouldn't make any difference in video performance. It's purpose is centralized authentication.

The machine on which I'm typing this is an i5-750 with 4GB of RAM and an nVidia 9800GTS video card running Fedora 12. Firefox and Flash are quite piggy so especially if I have a bunch of tabs open in Firefox, I can notice degradation in video playback performance. Higher resolutions only exacerbate the problem. If this is an issue on a reasonably fast machine like the machine I'm using where data doesn't have to traverse a network, you can imagine that once packets have to be pushed across a network, even if it's a Gigabit network, you'll have problems. In fact, a handful of thin-clients playing a YouTube video will bring even a fast server to its knees, if the network isn't saturated first. At the school at which I volunteer, the school administration was complaining loudly one day when anything they attempted to do on the network, such as accessing the file server or checking email, would take intolerably long and in some cases, time out. I checked the mrtg graphs for the day in question and saw two spikes in network traffic, one in the morning and another in the afternoon and asked the IT Coordinator to find out what was going on at those times. Apparently, a few of the teachers were streaming FIFA World Cup games over the Internet and that was enough to saturate the Gigabit network to the point where other network services were adversely affected.

The solution to the original poster's problem is apparently specifying that certain apps, like Firefox, should run locally on the thin-client. I've only read about it and haven't done it so you'll have to do your own tests to confirm.

Clifford Ilkay
1419-3266 Yonge St.
Toronto, ON
Canada  M4N 3P6

+1 416-410-3326

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