perfSONAR User Q&A and Other Discussion

[Andrew Lake <>]

Hi,

The error message in the web UI is likely a direct result of cassandra working correctly and not. That’s the section of the page that grabs the test results from esmond, which is the component talking to cassandra. The “Internal server” error you get when you are in IPv6 only mode is because cassandra is not working and it can’t determine if you have any results or not. When you add the IPv4 address, the “no test results” message implies that cassandra is working, but esmond is not finding any test results…which isn't entirely unexpected because your archive had been going in and out. 

For the issue with cassandra not work with IPv6-only I have created an issue since obviously we need to tinker with some settings to get this work right: https://github.com/esnet/esmond/issues/67. 

For the issue where you are not getting test results when you do the IPv4 trick, it's quite possible you just need to wait and the results will fill-in. You can start by looking in /var/log/pscheduler/pscheduler.log for errors. You can also do some basic tests at the command-line like “pscheduler task rtt —dest <remote-ip>” to do a simple ping test and/or “pscheduler task throughput —dest <remote-ip>” to see if you get results from iperf. Those *should* work but if they throw an error it may be indicative of another problem.

Thanks,

Andy

On October 6, 2017 at 2:28:50 PM, Trond Endrestøl () wrote:

On Fri, 6 Oct 2017 20:18+0200, Trond Endrestøl wrote:

> On Fri, 6 Oct 2017 10:49-0400, Andrew Lake wrote:
>
> > I think there is indeed an issue with cassandra’s default config and
> > IPv6-only hosts. Can you try the following:
> >
> > 1. Open /etc/cassandra/conf/cassandra-env.sh
> > 2. Find and comment-out the line JVM_OPTS=“$JVM_OPTS -Djava.net
> > .preferIPv4Stack=true”
> > 3. Save the changes.
> > 4. Restart cassandra with systemctl restart cassandra
> >
> > Might want to double check there are no other references to
> > -Djava.net.preferIPv4Stack=true
> > in that file, mine just had the one. Also since you have been changing
> > /etc/hosts, make sure localhost still resolves to ::1. Its possible we may
> > need to play with the Java opts some more, but hopefully that is all you
> > need. Seems to be a known issue with cassandra. We aren’t the authors of
> > the cassandra RPM, but if that indeed fixes your issue we can look at
> > having one of our packages correct that issue on install (it won’t be the
> > first time we have had to some hand-holding for cassandra’s RPM).
> >
> > Also, as an aside, there should be no requirement to disable your firewall.
> > I think you said that didn’t work anyways but all communication with
> > cassandra is done on localhost and should not be affected by the host
> > firewall.
>
> I reverted all my IPv4 perversion, commented out the IPv4Stack line in
> /etc/cassandra/conf/cassandra-env.sh, and rebooted the whole system.
>
> Cassandra might be running IPv6 only now, but the web interface shows
> Error loading test listing: Internal Server Error. Previously it
> showed something else, but no results from any test.

I added my fake IPv4 address, and restarted Apache. Still no
improvement. I made the IPv4 address resolvable via /etc/hosts, and
restarted Apache again. Now the web interface shows "Test Results (No
Results)". Maybe it's time to tinker with /etc/httpd/*.

--
Trond.