On 12/01/2008, Krsnendu dasa <[EMAIL PROTECTED]> wrote: > > I have noticed a few other problems and narrowed down the problem (I > think) to either os problem or motherboard problem. (Don't think it is the > switch or the network card.) Read below for more details. Thanks for all > tips. > > On 07/01/2008, Gavin McCullagh <[EMAIL PROTECTED]> wrote: > > > > Hi, > > > > On Mon, 07 Jan 2008, Krsnendu dasa wrote: > > > > > I am experiencing an unusual problem. Occasionally (every 15 mins or > > so) all > > > the terminals just disconnect. The terminals need restarting before > > they > > > work again. > > > > What you say all, you mean every thin client connected to the server? > > > Yes. Also windows computers that were connecting to the internet and using > dns through the edubuntu server also had disconnection problems. I changed > dhcpd.conf to get dns from another server and it seemed to fix the windows > laptop to internet problem. > I am having intermittent problems with samba also. One minute I can > connect to the shares on edubuntu then the next minute I can't then I can > again. It seems to take a long time for the server to register when new > windows computers in the workgroup have connnected. At one point I noticed > that nmbd wasn't running so I manually restarted it. This is after I had > already restarted samba using init.d and webmin. > > Every 15 minutes is pretty nasty. I guess at least it's easy enough to > > repeat if you're testing. > > > May not be exactly every 15 minutes, maybe closer to 30mins. > > You say the clients need restarting and I gather the server doesn't. Can > > you ping a thin client after this happens (ie without rebooting it)? If > > you press <ctrl><alt><backspace> is that enough to restart the thin > > client? > > > I haven't tried this as I haven't been at school much. I will try it next > time I am at school when it freezes. > > > In what I think may be a related issue, some times when someone is > > logged in > > > their terminal freezes and the panel at the bottom of the screen which > > shows > > > which windows are open just has three tabs that all say untitled > > window. > > > > Have you had opportunity to watch top for a few minutes and see does > > some > > process go wild around this point? > > I haven't noticed anything. I will look again and see if anything stands > out. > > > Background: I am using 32 Edubuntu 7.04 on Intel Quad Core. 4 Gb RAM. I > > am > > > using directx ldm and smbldap. > > > > Would it be possible for you to try not using direct-x and go back to > > the > > default ssh method? > > > I can also try this, but my instinct (and the dns /samba problems) seem to > point to bigger connection problems than ldm. > I also get disconnected when I log in from home using nx. > > > I am using a 100/1000 unmanaged switch which feeds 10/100 switches in > > each > > > class. > > > > > > Things I have already tried. > > > At first I thought it could be the 1000 switch, so I swapped it for > > another > > > one, but the problem remains. > > > > Was it another similar switch? Could it be a problem between the > > switches? > > > The second time I used a different brand of switch and a 10/100 switch, so > I don't think the switch is to blame. > > > Possible solutions: > > > Could upgrading to Gutsy help? > > > > It's hard to say without knowing what the cause of the problem is. > > > If may be my old windows conditioning, but I feel like a reinstall might > help... or not. > > > Could it be the network card in the server? > > > > Sounds plausible. > > > I tried another network card and the same problems are there. > > > > Can someone help me debug this? Are there any log files I can check to > > trace > > > the origin of this problem? > > > > Yes: > > /var/log/syslog > > /var/log/messages > > /var/log/kern.log > > /var/log/daemon.log > > > I had a look there and couldn't find anything that stood out for me. A few > times I saw something that said "disconnected" or something like that. > Perhaps I will copy and paste a section around the time when a disconnect > happens and post it for any experts to analyse. > > > Thanks for any help. This is really frustrating, because I had a very > > stable > > > system with K12LTSP 6, and now with Edubutnu 7.04 I have having quite > > a few > > > problems. > > > > How long have you had this problem? You've been using 7.04 for a while, > > right? Has it always happened? Has anything changed to prompt this? > > > We installed some time in October. This problem has been only since > December. I can't think of anything that changed at that time. The last > thing I remember that changed is... A course management software web-based > application was installed and there were some changes to dns. >
Back to the drawing board... I have installed Hardy and the problem persists. I will have to investigate the network and system more thoroughly and document it robustly. Summary: Initial Problem: Feisty install of Edubuntu - One Network interface: Server randomly disconnects from the network about every 20-30 mins. Terminals left with 3 unusual untitled windows tabs at the bottom of the screen. ALT-Ctrl-backspace usually allows users to log in again. Tried using another network card, switch etc. Ran Wireshark to look for network problems. Tried changing the system to a new box. Problem persists. SSH mostly seems affected. Even when I can ping the server I can't ssh in. A few minutes later I can ssh in. At the same time I can ssh in from one machine, but not from another machine. Sometimes the server can ping a machine, but that machine cannot ping the server. I installed Hardy with 1 network card: problem persists.
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