Hi,
We are experiencing an issue on our Rocky 9 NFS server and Rocky 8,
Rocky 9 and Fedora 41 clients.
The server is (now) running upstream Linux 6.11.11 and the Fedora 41
clients are running the Fedora 6.11.11 kernel. The Rocky 8 and 9
machines are running the latest Rocky 8/9 kernels.
Suddenly, a number of clients start to send an abnormal amount of NFS
traffic to the server that saturates their link and never seems to stop.
Running iotop on the clients shows kworker-{rpciod,nfsiod,xprtiod}
processes generating the write traffic. On the server side, the system
seems to process the traffic as the disks are processing the write requests.
This behavior continues even after stopping all user processes on the
clients and unmounting the NFS mount on the client. Is this normal? I
was under the impression that once the NFS mount is unmounted no further
traffic to the server should be visible?
Not all clients seem to trigger this issue. On a Fedora 41 client that
(auto)mounts home directories from the NFS server the behavior seems to
be triggered when I start Thunderbird and let it process a lot of new
mail (mail from the IMAP server is stored in the thunderbird cache
that's stored in the nfs-mounted home directory). This triggers the high
write traffic of the kworker threads. At first, thunderbird behaves
normally but gets really slow over time. Stopping thunderbird does not
stop the kworker threads and they keep sending a lot of traffic to the
server.
Can you point me to some steps to further diagnose this? Where can I
find what triggers the creation of these kworker threads? Why does iotop
show the write traffic with these threads, and not the thunderbird threads?
There haven't been many changes to our kernels on the Rocky side
recently. Is it possible a Fedora 41 client running a more recent kernel
somehow triggers a behavior on the server that results in Rocky clients
to start to misbehave?
Regards,
Rik
--
Rik Theys
System Engineer
KU Leuven - Dept. Elektrotechniek (ESAT)
Kasteelpark Arenberg 10 bus 2440 - B-3001 Leuven-Heverlee
+32(0)16/32.11.07
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