kernel: 2.4.28 smp x86_64
Hello,
We experience a problem in our amd64 beowulf clusters and could need some help. When ping'ing other machines in a cluster on the same subnet, it fails for some machines. But only right after boot and after a day or so of idle time. After some time (a few minutes) the ping packets go through.
Other things we observed:
1. it is not always the same machines that fail 2. if it fails then no packets are sent or received (checked with tcpdump on sending and target host) although all hosts are up. 3. There is no difference if using a 64bit or 32bit ping 4. It does not depend on the network adapter or other hardware, we have machines with different NICs connected to different switches with the same problem. 5. It does however only happen on amd64 (biarch) systems and not on pure i386 systems so it looks like related to the kernel. 6. I have to reboot to reproduce the problem, it's not enough to unload and load the network module. 7. It only happens with ping, not with ssh.
The ping always succeeds when running with the "-r" switch, that bypasses "the normal routing tables and send directly to a host on an attached interface". This makes us think that it indeed it is related to routing - but how?
I can provide an strace output if you think that could help. What else can I do to gather more information?
Please cc to me, as I'm not subscribed, thanks.
Peter
-- Peter Kruse <pk@xxxxxxxxxx>, Chief Software Architect Q-Leap Networks GmbH phone: +497071-703171, mobile: +49172-6340044
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