Re: NFS-SWAP
Jonas Smedegaard skrev:
Sorry - it was not my intention to question the truth of your info.
No offense taken :-)
Let me put it differently: Do you recall the setup of those thin clients
stabilizing with NFS-swap enabled? Did they have 32MB ram or even less
than that? Did they use 10Mbit or 100Mbit NICs? PCI bus? Do you recall
the brand and name of the the machines?
There were mostly old Dell recycled PCs. They varied wildy in spec, from
P75/16MB RAM to P3s with 256 MB RAM. If you are coming to the Skolelinux
developers meet at then end of the month, I can show you. The clients
are at that school. The lab had stability problems, the symptoms were
classic low-memory: clients would work for a while, then suddenly
without warning "restart". The user would lose the work, and be
presented with a login screen. Now, the reason I say this is classic is
that this is the Linux kernel at work. The machine gets low on memory,
the kernel senses a problem and starts killing off processes. In a thin
client there aren't that many to choose from, so it takes the most
memory-hungry: X. The result is that the screen goes blank, and KDM
picks up the pieces. As technicians we stand around marvelling at this
piece of software: the kernel actually makes sure the OS is protected.
No blue screen of death here. The user is less impressed, naturally,
having lost all her work.
Enabling NFS has cured this "feature", now the kernel can revert to swap
as virtual memory and swaps out pieces of the X server rather than
killing it. Stability is now very good, even if some people wrinkle
their noses at this slow swap solution it is never used much, and is in
practice not slowing down the clients, and not creating much network
traffic.
Off course, if you refer to "a whole bunch of different setups all
behaving exactly the same" then my question is irrelevant - but that
info is indeed relevant (so that I waste no more time digging into this).
I guess this is true, lots of different clients all behaving the same.
There should not be a need to dig too deep, it's a simple problem to
both diagnose and solve. If you have thin clients with RAM >= 32 MB RAM,
use NFS swap :-)
It is possible with LTSP used in Skolelinux to enable local access to
floppy drives and sound hardware, and to execute some applications
locally on the clients. Do you recall wether or not you used any of
those features on your "memory challenged" thin clients?
No, as I said, no local stuff.
If you don't recall that, but usually enable those features generally
that is valuable info as well :-)
Skolelinux has nfs swap enabled as default by settings in lts.conf
--
Med vennlig hilsen
Ragnar Wisløff
-------------
Life is a reach. Then you gybe.
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