grr@cbmvax.UUCP (George Robbins) (11/21/89)
A week or so there were some questions about runaway nfs daemons.
Well today, we had this occur here, luckily on some suns rather than
my crash happy ultrix system...
The server was a Sun-4 with several Sparcstations and a Sun-3 as
clients. The symptoms were the server completely bogged down,
with character echo over a telnet connection taking 15-20 seconds,
and occasional "server not responding" messages on the clients.
Judging from the blinking lights on some of the thin-wire ethernet
repeats, the ethernet was running constantly, though other traffic
was getting through without obvious problems, though there were some
after the fact complaints about "poor performance all day". The server
was configured with 8 nfs deamons, and and ps showed all 8 in "S" state
and accumulating cpu time, with the load index > 9...
Two of the clients were also running up cpu time, both were "logged out",
however a ps showed that each still had a copy of gnu-emacs that was
logging the cpu time.
After blowing away the clients, everything returned to normal on the
server.
The moral seems to be that any half-juiced clint can completely bog
down a server, since the work done by the server great in comparison
to that of issuing requests. Also, it looks like one or two clients
can eat all the nfs deamons, though I don't know if this is "normal"
or a result of some unusual perversity on the part of gnu-emacs.
It looks like there may be enough potential sources of this sort of problem
that all you can do is make an effort to see what is really happening
between server and client and try to resolve the problem from the client
side, in this case see why gnu was still running after the "logout"
and educate the users. The Sun tcpdump and etherfind ultilities plus
the indicator lights on bridges and/or transceivers can be quite helpful
in identifying the conspiring parties.
--
George Robbins - now working for, uucp: {uunet|pyramid|rutgers}!cbmvax!grr
but no way officially representing arpa: cbmvax!grr@uunet.uu.net
Commodore, Engineering Department fone: 215-431-9255 (only by moonlite)