I'm forwarding this message from my good friend Uwe Thiem, who is one of the original core KDE developers, as well as a contributor, tester and implementer of OpenLab+LTSP.
Perhaps this is change should be considered in the main LTSP tree. Ciao A.J. ---------- Forwarded Message ---------- Subject: idle clients flood the network - possible solution Date: Wednesday, 13 October 2004 12:19 From: Uwe Thiem <[EMAIL PROTECTED]> Hi folks, Kathy, I am CCing this to you FYI. It's pretty technical, decide for yourself whether it is worth your time to read it. ;-) I digged through a lot fo docs regarding LTSP and NFS and think I know now why idle thin clients are flooding the network. I even think I know how to lessen this unnecessary network load but ... there always is a but. See below. When a thin client starts up, it loads the kernel from the server and an initial ramdisk called initrd which it mounts as "/". Initrd contains a script called linuxrc that is executed immediately after mounting initrd. Amoung other things, linuxrc mounts server:/opt/ltsp/i386 via NFS on the ramdisk. (It will later make /opt/ltsp/386 "/" but that is irrelevant here.) Tfhe NFS protocol requieres clients to cache directory and file attributes of the mounted filesystem for a certain period of time. After a timeout (min 3s max 60s for files and min 30s max 60s for directories), the client will request the attributes from the server anew. And this is causing our network flooding with enough clients. :-( In our case, it is pretty unnecessary traffic because the attributes of objects under /opt/ltsp/i386 won't change at all. A possible solution would be to have an fstab in initrc that redefines the timeouts (namely acregmin, acregmax, acdirmin and acdirmax) in its nfs entry. For the benefit of SchoolNet and DireqLearn, I would actually be very willing to check whether practice agrees with my theory. :-) Problem is, I do not have access to the content of initrd. :-( I think of this as a design flaw in LTSP. They should have thought of it and pushed the timeouts up to an hour or some such. Kathy, I warned you in beforehand that this would get very technical. :-) Uwe -- Alternative phrasing of the First Law of Thermodynamics: If you eat it, and don't burn it off, you'll sit on it. http://www.schoolnet.na http://www.uwix.iway.na (last updated: 02.05.2004) ------------------------------------------------------- -- A.J Venter Lead Developer, DireqLearn 082 726 5103 http://www.direqlearn.org http://www.direqlearn.net/olce http://silentcoder.co.za ------------------------------------------------------- This SF.net email is sponsored by: IT Product Guide on ITManagersJournal Use IT products in your business? Tell us what you think of them. Give us Your Opinions, Get Free ThinkGeek Gift Certificates! Click to find out more http://productguide.itmanagersjournal.com/guidepromo.tmpl _____________________________________________________________________ Ltsp-discuss mailing list. To un-subscribe, or change prefs, goto: https://lists.sourceforge.net/lists/listinfo/ltsp-discuss For additional LTSP help, try #ltsp channel on irc.freenode.net
